Portable Dialysis Machine with Improved Reservoir Heating System

ABSTRACT

The specification discloses a portable dialysis machine having a detachable controller unit and base unit with an improved reservoir heating system. The controller unit includes a door having an interior face, a housing with a panel, where the housing and panel define a recessed region configured to receive the interior face of the door, and a manifold receiver fixedly attached to the panel. The base unit has a reservoir with an internal pan and external pan, separated by a space that holds a heating element. The heating element is electrically coupled to electrical contacts attached to the external surface of the external pan.

CROSS REFERENCE

The present application is a continuation-in-part of co-pending U.S.patent application Ser. No. 13/023,490 (the “'490 application”), filedon Feb. 8, 2011 and entitled “Portable Dialysis Machine”.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/237,914, filed on Sep. 25, 2008, which relies onU.S. Patent Provisional Application No. 60/975,157 filed on Sep. 25,2007 for priority.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/610,032, filed on Oct. 30, 2009, which relies onU.S. Patent Provisional Application No. 61/109,834 filed on Oct. 30,2008 for priority.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/324,924, which relies on, for priority, U.S.Provisional Patent Application No. 60/990,959, entitled “System andMethod of Changing Fluidic Circuit Between Hemodialysis Protocol andHemofiltration Protocol”, filed on Nov. 29, 2007 and U.S. ProvisionalPatent Application No. 61/021,962, of the same title, filed on Jan. 18,2008.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/249,090, which relies on, for priority, U.S.Provisional Patent Application No. 60/979,113, entitled “Photo-AcousticFlow Meter”, filed on Oct. 11, 2007.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/575,449, which relies on, for priority, U.S.Patent Provisional Application No. 61/103,271, filed on Oct. 7, 2008,for priority.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/751,930, which relies on, for priority, U.S.Patent Provisional Application No. 61/165,389, filed on Mar. 31, 2009.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/705,054, which relies on, for priority, U.S.Patent Provisional Application No. 61/151,912, filed on Feb. 12, 2009.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/875,888, which is a divisional of U.S. patentapplication Ser. No. 12/238,055, which relies on, for priority, U.S.Patent Provisional Application No. 60/975,840, filed on Sep. 28, 2007.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/210,080, which relies on, for priority, U.S.Patent Provisional Application No. 60/971,937, filed on Sep. 13, 2007.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/351,969, filed on Jan. 12, 2009.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/713,447, which relies on, for priority, U.S.Patent Provisional Application No. 61/155,548, filed on Feb. 26, 2009.

The '490 application is a continuation-in-part of U.S. patentapplication Ser. No. 12/575,450, which relies on, for priority, U.S.Patent Provisional Application No. 61/103,274, filed on Oct. 7, 2008.

All of the above listed specifications are herein incorporated byreference in their entirety.

FIELD OF THE INVENTION

The present invention is directed to a portable dialysis system withimproved structural and functional features. In particular, the dialysissystem of the present invention is directed to a portable dialysissystem with improved modularity, ease of use, and safety features.

BACKGROUND

Blood purification systems, which are used for conducting hemodialysis,hemodiafiltration or hemofiltration, involve the extracorporealcirculation of blood through an exchanger having a semi permeablemembrane. Such systems further include a hydraulic system forcirculating blood and a hydraulic system for circulating replacementfluid or dialysate comprising the certain blood electrolytes inconcentrations close to those of the blood of a healthy subject. Most ofthe conventionally available blood purification systems are, however,quite bulky in size and difficult to operate. Further, the design ofthese systems makes them unwieldy and not conducive to the use andinstallation of disposable components.

Standard dialysis treatment, using an installed apparatus in hospitals,comprises two phases, namely, (a) dialysis, in which toxic substancesand scoriae (normally small molecules) pass through the semi-permeablemembrane from the blood to the dialysis liquid, and (b) ultrafiltration,in which a pressure difference between the blood circuit and thedialysate circuit, more precisely a reduced pressure in the lattercircuit, causes the blood content of water to be reduced by apredetermined amount.

Dialysis procedures using standard equipment tend to be cumbersome aswell as costly, besides requiring the patient to be bound to a dialysiscenter for long durations. While portable dialysis systems have beendeveloped, conventional portable dialysis systems suffer from certaindisadvantages. First, they are not sufficiently modular, therebypreventing the easy setup, movement, shipping, and maintenance of thesystems. Second, the systems are not simplified enough for reliable,accurate use by a patient. The systems' interfaces and methods of usingdisposable components are subject to misuse and/or errors in usage bypatients. For a portable dialysis system to be truly effective, itshould be easily and readily used by individuals who are not health-careprofessionals, with disposable input and data input sufficientlyconstrained to prevent inaccurate use.

One conventional design of dialysis systems uses a single pass system.In single pass systems, the dialysate passes by the blood in thedialyzer one time and then is disposed. Single pass systems are fraughtwith a plurality of disadvantages, arising from the use of large amountsof water. First, assuming a 50% rejection rate by the R.O. (ReverseOsmosis) system, at least 1000 to 1500 ml/min of water is required.Second, a water purification system for providing a continuous flow of100 to 800 ml/minute of purified water is required. Third, an electricalcircuit of at least 15 amps is required, in order to pump 100 to 800 mlof water/minute, and, fourth, a floor drain or any other reservoircapable of accommodating at least 1500 ml/min of used dialysate and ROrejection water.

Conventional systems are also less reliable because of the necessity ofusing a myriad of tubes comprising the fluid circuits of thepurification systems, thus increasing the risks of leakage and breakage.In addition to being difficult to transport due to their large size,conventional dialysis machines also suffer from a lack of flexibility.For example, sorbent based hemodialysis procedures have a particular setof hardware requirements that are not shared by the hemofiltrationprocess. Thus, it would be beneficial to have common hardware componentssuch as the pumping system, which can be used such that the dialysissystem can be operated in hemofiltration as well as hemodialysis modes.

The tubes of the pump system are also subject to increased wear andsubsequent breakage due to slippage across the surface of the pumprollers. Prior art approaches have used individual spikes which extendup from the roller surface and are spaced apart equidistantly to keepthe tubes from veering back and forth across the roller surface.However, the spiked roller system is costly and difficult tomanufacture. Therefore, a need exists for a reliable and cost-effectivesystem for preventing lateral movement of the tube across the rollersurface.

Additionally, there is a need for a portable system that can effectivelyprovide the functionality of a dialysis system in a safe,cost-effective, and reliable manner. In particular, there is a need fora compact dialysis fluid reservoir system that can satisfy the fluiddelivery requirements of a dialysis procedure while integrating thereinvarious other critical functions, such as fluid heating, fluidmeasurement and monitoring, leak detection, and disconnection detection.

With respect to fluid heating in particular, known methods often use asingle heating coil positioned at the base of the reservoir. This canresult in slow and uneven heating. Therefore, there is a need for areservoir system that can rapidly and evenly heat the fluid. Inaddition, the reservoir system should have all the conductive elementsisolated from the fluid and needs to be easily accessible for removaland installation by users.

With respect to disconnection detection in particular, the effectivedetection of a return line disconnect is difficult, as most knownmethods are based on monitoring and detecting a change in pressure inthe venous return line tubing. Return line disconnection usually occursdue to a needle pull out situation. Since a needle typically offers thehighest fluidic resistance in an extracorporeal blood circuit, apressure change in the return line due to needle disconnect is notsignificant and cannot be detected easily. The pressure drop is alsovery low in cases where a catheter disconnects from a patient's body,causing a return line disconnection. Hence, detection of a disconnectionin a return venous blood circuit using pressure as an indicator ormetric is unreliable and may result in serious injury. Further, methodsusing detection of air bubbles as an indication of a disconnect cannotbe relied upon because a disconnect in a venous return line does notcause air to be drawn in the return line tubing. Consequently, there isneed for an improved apparatus and method for detecting a disconnect ina venous return line. Further, there is also need for an apparatus andmethod which does not require any extra element, such as a moisture padto be placed at the needle insertion site.

Additionally, there are no satisfactory mechanisms in the prior art formaintaining volumetric accuracy during the dialysis process that can beeasily implemented at a reasonable cost. Most of the prior art methodsfor maintaining volumetric accuracy of replacement fluid and outputfluid are not suited for use with disposable devices. One prior artapproach for maintaining volumetric accuracy involves weighing both thereplacement fluid and output fluid. However, this approach is difficultto implement in practice. Another prior art method comprises the use ofvolumetric balance chambers for dialysis systems. Such chambers are,however, complex and expensive to build and also not suitable fordisposable devices. Volumetric flow measurements are another knownmethod, but the accuracy of this method is not proven. Further, thismethod is very difficult to implement for a dialysis system indisposable form. Another prior art approach involves using two pistonpumps to achieve volumetric accuracy. However, this approach isextremely difficult to implement at a reasonable cost in disposableform, and is also not economical to operate at the required pumpingvolumes, which are of the order of 200 ml/min. There is therefore a needfor a method and a system that can be used to accurately maintain thevolume of the fluid infused into and removed from the patient, and whichcan be implemented inexpensively.

Furthermore, there is a need for a multiple-pass sorbent-based dialysissystem that lowers the overall water requirements relative toconventional systems. There is also a need for a manifold that can beused in a single pass sorbent-based dialysis system as well as in themultiple-pass system of the present invention, which offers alightweight structure with molded blood and dialysate flow paths toavoid a complicated mesh of tubing.

It is also desirable to have a portable dialysis system that has astructural design configured to optimize the modularity of the system,thereby enabling the easy setup, movement, shipping, and maintenance ofthe system. It is further desirable to have system interfaces, throughwhich patients input data or deploy disposable components, configured toprevent errors in usage and sufficiently constrained to preventinaccurate use.

SUMMARY

In one embodiment, the specification discloses a dialysis machinecomprising a controller unit wherein said controller unit comprises adoor having an interior face, a housing with a panel wherein saidhousing and panel define a recessed region configured to receive saidinterior face of said door, and a manifold receiver fixedly attached tosaid panel and a base unit wherein said base unit comprises a planarsurface for receiving a container of fluid, a scale integrated with saidplanar surface, a heater in thermal communication with said planarsurface, and a sodium sensor in electromagnetic communication with saidplanar surface.

Optionally, the manifold receiver comprises at least one of contouredguides, pins, or latches. The panel is configured to provide access to aplurality of pumps. The panel is configured to provide access to fourperistaltic pumps in substantially parallel alignment. The interior facecomprises four pump shoes. When the door is received into said recessedregion, each of said four pump shoes aligns with one of said fourperistaltic pumps. At least one of said pump shoes is movably attachedto said door by a member and spring. The member is a bolt.

Optionally, the controller unit further comprises a sensor for measuringmovement of said member. The controller unit further comprises acontroller for receiving a measure of the movement of said member fromthe sensor and determining a fluid pressure based on said measure.

Optionally, the machine is configured to perform a dialysis treatmentusing approximately six liters of water, wherein said water is from anon-sterile source. The manifold receiver is configured to receive amolded plastic substrate that defines a first flow path which isfluidically isolated from a second flow path. Each of said first andsecond flow paths has a hydraulic diameter in a range of 1.5 mm to 7.22mm. The molded plastic substrate is bonded to a plurality of tubing andwherein said plurality of tubing is bonded to a dialyzer. The controllerunit further comprises a member connected to an exterior of saidhousing, wherein said member is configured to physically receive saiddialyzer.

Optionally, the base unit further comprises a member connected to anexterior of said base unit, wherein said member is configured tophysically receive said dialyzer. The plurality of tubing is adapted tobe removably attached to a sorbent cartridge. The base unit furthercomprises a member connected to an exterior surface of the base unit,wherein said member is configured to physically receive the sorbentcartridge. The controller unit comprises a bottom surface, wherein saidbottom surface comprises a first physical interface and a first datainterface.

Optionally, the base unit has a top surface and wherein said top surfacecomprises a second physical interface configured to complement saidfirst physical interface and a second data interface capable ofinterfacing with said first data interface. The scale comprises aplurality of flexures and hall sensors, wherein each of said flexures isin physical communication with said planar surface and wherein each ofsaid hall sensors is configured to sense a physical displacement. Thesodium sensor comprises a conductivity sensor.

Optionally, the conductivity sensor comprises a coil having a pluralityof turns, a capacitor in electrical communication with said coil,wherein said coil and capacitor define a circuit, and an energy sourcein electrical communication with said circuit. The conductivity sensoroutputs a value indicative of a sodium concentration in said fluid basedon an energy input required from said energy source to maintain theconstant voltage across the capacitor.

Optionally, the base unit comprises at least one moisture sensor. Thebase unit comprises a door capable of being in an open state or in aclosed state and wherein the door is physically blocked from being inthe open state when said interior face of the door is received in therecessed region. The base unit comprises a door capable of being in anopen state or in a closed state and wherein the door is physicallylocked into the closed state when said interior face of the door is insaid recessed region. The controller unit comprises a plurality ofsensors in communication with a molded plastic substrate when saidinterior face of the door is in said recessed region. At least one ofsaid plurality of sensors comprises a pressure transducer. The pressuretransducer is in pressure communication with a flexible membraneintegrated into said molded plastic substrate.

Optionally, the controller unit comprises at least one valve componentin communication with said molded plastic substrate. The controller unitcomprises a plurality of programmatic instructions configured toactivate the valve component and wherein activation of said valvecomponent causes fluid flow to be directed through one of two separatefluid paths in said molded plastic substrate. The activation of thevalve component is dependent upon a mode of operation of the bloodpurification system.

Optionally, the valve component has an open position and a closedposition and wherein said valve component comprises an orifice closingmember adjacent to an orifice through which fluid can flow, adisplacement member having a first portion and a second portion, whereinsaid first portion is adjacent to the orifice closing member when avalve component is in said open position, a first magnet and a secondmagnet wherein said first and second magnets are sufficiently proximateto said displacement member to exert a magnetic force on saiddisplacement member, and an actuator for generating a magnetic field tomove said displacement member toward said first magnet, cause said firstportion to press against the orifice closing member, and cause theorifice closing member to close said orifice.

Optionally, the first portion comprises a housing, elastic material, arod and a gap between said elastic material and said rod. An opticalsensor is positioned to sense if a gap in said valve component ispresent or absent. The first portion comprises a rod and said secondportion of said displacement member is a metal body with a diametergreater than said rod. The rod is bonded to a cylinder. The first magnetis larger than said second magnet. The orifice closing member comprisesat least one of a diaphragm, an elastic material, and a compressiblematerial. The orifice closing member compresses against a valve seat toclose said orifice.

Optionally, the valve component comprises an orifice closing memberadjacent to an orifice through which fluid can flow wherein said orificeclosing member compresses against a valve seat when the valve is in aclosed position, a moveable member that is physically movable relativeto said orifice closing member wherein said moveable member moves from afirst position when said valve is in an open position to a secondposition when said valve is in said closed position and wherein, in saidsecond position, the moveable member presses against the orifice closingmember to cause said orifice closing member to compress against thevalve seat, a first magnet and a second magnet having a separationwherein said first magnet and second magnet generate a magnetic field inthe separation and wherein said magnetic field has a direction, and anactuator capable of generating an electromagnetic force, wherein saidelectromagnetic force reverses the direction of said magnetic field.

Optionally, the dialysis machine comprises an optical sensor positionedto sense if a gap is present or absent. The first magnet and secondmagnet provide a bearing surface for movement of said moveable member.The first magnet, having a first pole, is larger than said secondmagnet, having a second pole. The first pole and second pole repel eachother and wherein the first magnet and second magnet are configured tohave said first pole and second pole face each other.

Optionally, the controller unit further comprises a valve having a firststable state and a second stable state wherein said valve comprisesmagnets, wherein an input of energy into said valve creates a magneticforce which causes a displacement member to move within said controllerunit, wherein the movement of said displacement member causes a changebetween the first state and the second state, and wherein maintenance ofsaid first or second state does not require energy input.

Optionally, the molded plastic substrate has an orifice wherein saidorifice is closed to fluid flow when said valve is in the first stablestate and wherein said orifice is open to fluid flow when said valve isin the second stable state. The orifice is closed to fluid flow whensaid displacement member compresses a material into said orifice. Atleast one of said plurality of sensors is a flow meter.

Optionally, the flow meter comprises at least two probes, each of saidprobes having a body and a contact surface positioned on said moldedplastic substrate, wherein a first of said at least two probes generatesa thermal wave within fluid flowing through said molded plasticsubstrate in response to a first thermal signal and a second of said atleast two probes senses said thermal wave within said fluid. The flowmeter further comprises a reference signal generator, wherein saidreference signal generator outputs a reference signal. The flow meterfurther comprises a heat source, wherein said heat source receives saidreference signal from said reference signal generator, is configured tothermally engage with the first of said at least two probes, andgenerates said first thermal signal, having a phase derived from saidreference signal. The flow meter further comprises a temperature sensor,wherein said temperature sensor is configured to thermally engage withsaid second probe, and generate a second thermal signal, having a phasederived from said thermal wave. The flow meter further comprises amultiplier for receiving an input signal from said reference signalgenerator and for receiving said second thermal signal and foroutputting a third signal. The flow meter further comprises a low passfilter for receiving a signal derived from said third signal, and forreceiving the reference signal from said reference signal generator,wherein said low pass filter modulates its cutoff frequency based uponthe reference signal.

Optionally, the second probe is separated from said first probe by adistance of less than two inches. The dialysis machine further comprisesan amplifier for amplifying said third signal and generating the signalderived from said third signal. The body of each of said at least twoprobes has a diameter in the range of 0.03 inches to 0.15 inches. Thecontact surface of each of said at least two probes has a diameter inthe range of 0.025 inches to 0.2 inches. The second probe comprises athermistor. The low pass filter generates a filtered signal and whereinthe reference signal generator generates said reference signal based, atleast in part, on said filtered signal. The flow meter dynamicallyadjusts said reference signal in order to maintain a constant frequency.The flow meter dynamically adjusts said reference signal in order tomaintain a constant phase.

Optionally, the flow meter is configured to project an optical beam intofluid within said molded plastic substrate; detect a resultant acousticsignal at a first point upstream and at a second point downstream in thefluid; determine a phase difference between said acoustic signaldetected upstream and said acoustic signal detected downstream in thefluid; and, compute the rate of flow of said fluid from said determinedphase difference. The phase difference is determined by subtracting thesignals representative of said acoustic signal phase detected upstreamand downstream.

Optionally, the flow meter comprises an optical system for projecting anoptical beam into fluid flowing through a transparent section of saidmolded plastic substrate; a first acoustic detector for detecting theacoustic signal at a first point upstream from said transparent section;a second acoustic detector for detecting said acoustic signal at asecond point downstream from said transparent section; and, a processorfor determining a phase difference between said acoustic signal detectedupstream and said acoustic signal detected downstream and for computingfrom the determined phase difference a rate of flow of fluid in saidmolded plastic substrate.

The processor for determining the phase difference comprises asubtraction unit. The optical system is a pulsed laser system. Theoptical beam is projected perpendicular to the direction of flow of saidfluid. The flow meter has an operative sensing range between 20 ml/minto 600 ml/min. The flow meter has an operative sensing range between 20ml/min to 600 ml/min. The controller unit further comprises a reader fordetecting identification data embedded in a molded plastic substrate.The controller unit further comprises a temperature sensor which isadapted to be in thermal communication with a molded plastic substratewhen said door is in said recessed region.

Optionally, the controller unit comprises a disconnection monitor fordetermining if a blood line connection to a patient has beendisconnected. The disconnection monitor comprises a pressure transducerin pressure communication with a blood flow path in said manifoldwherein said pressure transducer generates a signal indicative of apulse signal in said blood flow path, a cardiac reference signalgenerator, wherein said cardiac reference signal generator detects andgenerates a signal indicative of said patient's pulse, a pressuretransducer data receiver, wherein said pressure transducer data receiverreceives said signal indicative of the pulse signal in said blood flowpath, a cardiac reference signal receiver, wherein said cardiacreference signal receiver receives said signal indicative of thepatient's pulse, and a processor, wherein said processorcross-correlates said signal indicative of the pulse signal in saidblood flow path and said signal indicative of the patient's pulse togenerate data indicative of a disconnection of the blood line connectionto the patient.

Optionally, the disconnection monitor further comprises a controller,wherein said controller triggers an alarm based upon said dataindicative of a disconnection of the blood line connection to thepatient. The disconnection monitor further comprises a controller,wherein said controller shuts down a dialysis pump based upon said dataindicative of a disconnection of the blood line connection to a patient.

Optionally, the pressure transducer non-invasively generates a signalindicative of a pulse signal in said blood flow path. The processorcross-correlates said signal indicative of the pulse signal in saidblood circuit and said signal indicative of the patient's pulse bycomputing a sum of products of corresponding pairs of points of thesignal indicative of the pulse signal in said blood circuit and saidsignal indicative of the patient's pulse within a specified time frame.

Optionally, the disconnection monitor further comprises programmaticinstructions for directing a patient to first attach said cardiac signalreference generator prior to starting a dialysis pump. The disconnectionmonitor further comprises programmatic instructions for directing thesystem to capture said signal indicative of the pulse signal in saidblood flow path prior to starting a dialysis pump.

Optionally, the controller unit further comprises a display, a scale, abar code reader, and a memory storing a plurality of programmaticinstructions wherein, upon execution, said instructions generate a) afirst graphical user interface for presentation on said display, whereinsaid first graphical user interface displays each additive required foruse in a dialysis treatment, b) a second graphical user interface forpresentation on said display, wherein said second graphical userinterface prompts a user of said system to submit a plurality ofadditives to scanning using said bar code scanner and c) a thirdgraphical user interface for presentation on said display, wherein saidthird graphical user interface prompts a user of said system to submit aplurality of additives to measurement using said scale.

Optionally, the scale is a digital scale. The bar code scanner providesa visual indication of a successful read. The memory further comprises atable associating a plurality of additive names with a plurality of barcodes. The memory further comprises a table associating a plurality ofadditives with a plurality of weight values. The first graphical userinterface displays a visual representation of the additive packaging.The third graphical user interface only prompts the user of said systemto submit an additive to measurement using said scale if a bar code ofthe additive is not recognized. The third graphical user interface onlyprompts the user of said system to submit an additive to measurementusing said scale if a bar code for the additive is not available.

Optionally, the controller unit further comprises a display, a scalecomprising a plurality of magnets, an electronic reader, and a memorystoring a plurality of programmatic instructions wherein, uponexecution, said instructions generate a) a first graphical userinterface for presentation on said display, wherein said first graphicaluser interface prompts a user of said system to submit a plurality ofadditives to scanning using said bar code scanner and b) a secondgraphical user interface for presentation on said display, wherein saidsecond graphical user interface prompts a user of said system to submita plurality of additives to measurement using said scale.

Optionally, upon execution, the instructions further generate a thirdgraphical user interface for presentation on said display, wherein saidthird graphical user interface displays each additive required for usein the dialysis treatment. The scale is a digital scale and wherein saiddigital scale generates data representative of a weight of an objectplaced on said digital scale. The digital scale further comprises atleast three flexures. Each of said flexures comprises a magnet and acorresponding hall sensor.

Optionally, the dialysis system further comprises a molded plasticsubstrate wherein said molded plastic substrate comprises a first flowpath and a second flow path defined therein and wherein said first flowpath and said second flow path are fluidically separated by a valve. Thecontroller unit further comprises a memory storing a plurality ofprogrammatic instructions, wherein said programmatic instructions areconfigured to define a first state of said valve and a second state ofsaid valve depending upon a selected mode of operation. The selectedmode of operation is either a priming mode or a treatment mode. Thefirst state of the valve places said first flow path in fluidcommunication with said second flow path. The second state of the valveplaces said first flow path in fluid isolation from said second flowpath. The dialysis system further comprises a molded plastic substratewherein said substrate comprises a first fluid circuit for infusingfluid into a patient and a second fluid circuit for removing fluid fromthe patient.

Optionally, the controller unit further comprises a first pumpconfigured to alternately operate on said first circuit and said secondcircuit; a second pump configured to alternately operate on said secondcircuit and said first circuit; and a controller for causing said firstpump to alternatively operate on said first circuit and said secondcircuit and for causing said second pump to alternatively operate onsaid first circuit and said second circuit, wherein each of the saidfirst pump and second pump operate only one circuit at a given time.

Optionally, the first pump causes a higher amount of fluid to be pumpedper unit time than the second pump. The first and second pumpsalternately operate on said first and second circuits for a timeinterval, wherein said time interval is derived from an allowabledifference in the amount of fluid pumped per unit time by the said firstand second pumps. The first and second pumps are peristaltic pumps. Thedialysis system further comprises a restrictor for equalizing a pressuredifferential between said first and second circuits. The restrictor isactive and equalizes said pressure differential based upon a measuredpressure differential derived from a first pressure sensor in said firstcircuit and from a second pressure sensor in said second circuit.

Optionally, the panel further comprises a funnel defined by two slopedsurfaces leading to a channel and wherein said channel comprises atleast one moisture sensor. When the door is received into said recessedregion, the funnel is located below the manifold and configured tochannel fluid leaking from said manifold toward said moisture sensor.

Optionally, the bottom surface of the controller unit is adapted to beremovably attached to a top surface of said base unit. The controllerunit is in electrical communication with the base unit. The controllerunit is physically detached from the base unit. The controller unit isin data communication with the base unit. The controller unit is influid communication with the base unit.

In another embodiment, the present invention is directed toward adialysis machine comprising a first unit wherein said first unitcomprises a door having a first face, a housing attached to said door,wherein housing has a second face, at least one manifold receiverfixedly attached to said second face, and a display for displaying agraphical user interface, and a second unit wherein said second unitcomprises a planar surface for supporting a container of fluid, aweighing means integrated with said planar surface, a heater in thermalcommunication with said planar surface, and a sodium sensor proximate tosaid planar surface.

Optionally, the manifold receiver is configured to receive a moldedplastic substrate that defines a first flow path which is fluidicallyisolated from a second flow path. The molded plastic substrate comprisesa first layer; a second layer; a first flow path defined by a firstsurface of the first layer and a first surface of the second layer; asecond flow path defined by a first surface of the first layer and afirst surface of the second layer; and a valve in fluid communicationwith both said first flow path and said second flow path wherein saidvalve has a first state and a second state and wherein, when in saidfirst state, the first flow path and second flow path are in fluidisolation and when in said second state, the first flow path and secondflow path are in fluid communication.

Optionally, the molded plastic substrate comprises a first plurality ofports in opposing alignment to a second plurality of ports. At least oneof said first plurality of ports and second plurality of ports comprisesa member having an external cylindrical housing, wherein said member hasan interior space defined by a central axis. The central axis is angledrelative to a plane within which said plastic substrate lies. The angleis in a range of 5 degrees to 15 degrees. At least one of said firstplurality of ports is defined by a cross-sectional area having a firstdiameter and a second diameter perpendicular to the first diameter. Atleast one of said first plurality of ports is connected to a portchannel defined by a cross-sectional area having a third diameter and afourth diameter perpendicular to the third diameter, wherein the thirddiameter is greater than the first diameter and wherein the fourthdiameter is less than the second diameter. The port channel comprises atleast one protruding member having a height less than the fourthdiameter. The port channel is covered by a flexible membrane. The portchannel comprises at least one protrusion configured to prevent aflexible membrane from collapsing into said port channel and completelyoccluding said port channel. The cross-sectional area of said portchannel is different from said cross-sectional area of said port and thecross-sectional area of said port channel is configured to maintain asubstantially constant velocity of fluid passing through said port andinto said port channel.

Optionally, the molded plastic is defined by a first segment, secondsegment, and third segment; wherein said first segment is parallel tosaid second segment; wherein said third segment is perpendicular to, andattached to, each of said first segment and second segment; and whereinsaid first, second, and third segments define a first flow path that isfluidically isolated from a second flow path.

Optionally, the first segment has a first plurality of ports and saidsecond segment has a second plurality of ports, and wherein said firstand second plurality of ports are in alignment. At least one of saidfirst plurality of ports and second plurality of ports comprises amember having an interior space defined by a central axis. The centralaxis is angled relative to a plane within which said first and secondsegments lie. The angle is in a range of 5 degrees to 15 degrees. Atleast one of said first plurality of ports is defined by across-sectional area having a first diameter parallel to a length of thefirst segment and a second diameter perpendicular to the first diameter.At least one of said first plurality of ports is connected to a portchannel having a cross-sectional area with a third diameter parallel tothe length of the first segment and a fourth diameter perpendicular tothe third diameter, wherein the third diameter is greater than the firstdiameter and wherein the fourth diameter is less than the seconddiameter. The port channel comprises at least one protruding memberhaving a height less than the fourth diameter. The port channel iscovered by a flexible membrane. The port channel comprises at least oneprotrusion configured to prevent a flexible membrane from collapsinginto said port channel. The cross-sectional area of said port channel isdifferent from said cross-sectional area of said port and thecross-sectional area of said port channel is configured to maintain asubstantially constant Reynolds number of fluid passing through saidport and into said port channel.

Optionally, the third segment is attached to a center of the firstsegment and the second segment. The third segment is not attached to acenter of the first segment or the second segment. The first segment hasat least one port wherein a portion of an interior of said port isdefined by a flat base. The first segment and said second segment have alength in a range of 4 to 7 inches and a width in a range of 0.5 to 1.5inches. The third segment has a length in a range of 2.5 to 4.5 inches.The first segment has a first length and a first width, said secondsegment has a second length and a second width, and said third segmenthas a third length and a third width, and wherein said first length andsaid second length are greater than the third width and said first widthand second width are less than the third length. The first segment has afirst length and a first width and said second segment has a secondlength and a second width, and wherein said first length is equal tosaid second length and said first width is equal to said second width.

Optionally, the manifold receiver is configured to receive a moldedplastic substrate and wherein a tubular segment connects said moldedplastic substrate with a dialyzer. The dialysis machine comprises areceiver to removably attach said dialyzer to an external surface ofsaid dialysis machine. The tubular segment comprises a disposableconductivity probe, having an internal volume, wherein said internalvolume receives fluid flowing through said tubular segment. Thedisposable conductivity probe is adapted to removably connect to matingprobes positioned on an external surface of said dialysis machine.

In another embodiment, the present invention is directed toward adialysis machine comprising a first unit in data communication with asecond unit, wherein said first unit comprises a door with a pressureplate positioned on an interior face of the door, a housing with a panelwherein said housing and panel define a recessed region configured toreceive said interior face of said door, an alignment mechanism fixedlyattached to said panel, wherein said alignment mechanism is configuredto detachably receive a manifold on said panel and position saidmanifold against said pressure plate when the door is received into saidrecessed region and wherein said second unit comprises a planar surfacefor receiving a container of fluid, a weighing means integrated withsaid planar surface, a heater in thermal communication with said planarsurface, and a sodium sensor proximate to said planar surface.

In another embodiment, the present invention is directed towards amultiple-pass, sorbent-based hemodiafiltration system, advantageouslycombining hemofiltration and hemodialysis in a multiple passconfiguration.

In another embodiment, the present invention is directed toward manifoldsupports for blood purification systems, such as, but not limited tohemodiafiltration and ultrafiltration. In one embodiment, the manifoldof the present invention comprises a composite plastic manifold, intowhich the blood and dialysate flow paths are molded. This plastic basedmanifold can be used with the multiple-pass sorbent-basedhemodiafiltration system of the present invention.

In another embodiment, blood purification system components, such assensors, pumps, and disposables are integrated into the molded manifold.Disposable items such as but not limited to dialyzer and sorbentcartridges, are detachably loadable on to, or in fluid communicationwith, the manifold. Disposable items such as but not limited to dialyzerand sorbent cartridges, are fixedly attached to tubing that is fixedlyattached to, and in fluid communication with, the manifold.

In yet another embodiment, an ultrafiltration system is integrated intoa manifold by molding both blood and ultrafiltrate flow paths in themanifold. In one embodiment, the manifolds disclosed herein comprisesingle, composite plastic structures, also referred to as substrates orhousings, that can be made by combining two plastic substrate halves.

In another embodiment, the present invention is directed towards adialysis system that supports an electronic-based lockout system.Accordingly, in one embodiment, a reader is mounted on the systemhousing(s) and/or manifold(s), such as but not limited to thehemodiafiltration and ultrafiltration manifolds, and readsidentification indicia on disposable items that are loaded onto thedialysis housing(s) and/or manifolds. The reader communicates with adatabase over a network, such as a public network or private network, tocheck if the disposable items are valid, accurate, or of sufficientintegrity to be safe and ready for use. This is done by queryinginformation on the disposable items from the remote database, based onthe identification indicia of the items. If the disposable item has an“invalid” or “compromised” status, (based on the information receivedfrom the database) the system “locks out” the use of the loadeddisposable, and thus does not allow the user to proceed with using thesystem for treatment.

The present specification is also directed toward a dialysis machinehaving a reservoir unit wherein said reservoir unit comprises: a firsthousing having an external surface and an internal surface and defininga first volume adapted to hold a fluid therein; a second housing havingan external surface and an internal surface and defining a second volumeadapted to house the first housing with a space between the externalsurface of the first housing and the internal surface of the secondhousing; a heating element positioned within the space between theexternal surface of the first housing and the internal surface of thesecond housing; and a first plurality of electrical contacts attached tothe external surface of the second housing and electrically coupled tothe heating element.

In one embodiment, the first housing is fused to said second housing. Inone embodiment, the heating element is a heating pad wherein saidheating pad is rated in a range from 300 W to 600 W. In one embodiment,the heating pad is configured to heat from 1 liter to 6 liters of afluid, located within said first volume, to a temperature within a rangeof 36 to 39 degrees C. within 15 to 45 minutes.

In one embodiment, the first housing is a pan and the first volume is atleast one of a cuboid, rectangular prism, right rectangular prism,rectangular parallelepiped, or any other volume having two sets ofparallel sides at substantially right angles with a base. The secondhousing is also pan and is defined by a second volume that is the sameshape as the first volume, but smaller, thereby permitting the second,smaller pan to fit within the first pan and leave a preferablyequidistant space between the internal sides of the first pan and theexternal sides of the second pan. While the volume is described in termsof sides at right angles to a base, it should be appreciated that thejoints can be substantially rounded or curved and still fall within thescope of the term cuboid, pan, rectangular prism, right rectangularprism, or rectangular parallelepiped.

In one embodiment, the first plurality of electrical contacts attachedto the external surface of the second housing are electrically coupledto the heating element by wires that extend from the heating elementthrough the second housing and into the electrical contacts.

In one embodiment, the dialysis machine further comprises: a base unit,having a length extending from a front of the base unit to the back ofthe base unit, wherein the base unit comprises a support point; a firstinternal frame connected to said support point, wherein said firstinternal frame comprises: a plate comprising a second plurality ofelectrical contact elements connected to a power supply of the dialysismachine; at least two first tracks, with each first track physicallycoupled to said plate and extending across the length of the base unit.

In one embodiment, the second housing comprises a plurality of top edgesand linear extensions perpendicularly extend from at least two of saidtop edges.

In one embodiment, the reservoir unit is installed in said dialysismachine by sliding the linear extensions onto the first tracks until apredefined insertion point. In one embodiment, upon the reservoir unitsliding on the first tracks and reaching said predefined insertionportion, the first plurality of electrical contact elementsautomatically electrically couples with said second plurality ofelectrical contact elements, without requiring any further action by auser.

In one embodiment, the first internal frame is only physically coupledto the base unit through the support point. In one embodiment, thesupport point comprises a flexure assembly, wherein said flexureassembly is used to measure the weight of contents of a reservoir unit.

In one embodiment, each of said at least two first tracks comprises apositioning tab demarcating a drop off section wherein said reservoirunit drops off of said tracks and into place when fully inserted intosaid reservoir unit support structure.

In one embodiment, the base unit further comprises a top with a bottomsurface and a second internal frame, said second internal framecomprising: a top plate attached to said bottom surface of said top ofsaid base unit; and, at least two second tracks, with each second trackphysically coupled to said plate and extending across the length of thebase unit.

In one embodiment, the second tracks are configured to suspend a ceilingelement, said ceiling element comprising: a lining bag configured torest in a reservoir unit and hold a liquid; at least one first tube fordrawing said liquid from said reservoir unit; and at least one secondtube for returning said liquid to said reservoir unit.

In one embodiment, the dialysis machine further comprises a door on afront of said base unit, wherein said door folds upward to close andfolds downward to open.

The present specification is also directed toward a pump shoe for apumping system having flexible tubing wherein said tubing is compressedagainst said pump shoe by a pump roller during operation, said pump shoecomprising: a contact surface for receiving said tubing, wherein saidcontact surface has a degree of curvature matching the curvature of saidpump roller and imparting a concave shape for receiving said tubing asit is compressed by said pump roller; an attachment surface oppositesaid contact surface for attachment of said pump shoe to said pumpingsystem; and, two side surfaces, opposite one another and perpendicularto said contact and attachment surfaces, wherein the edge of each sidesurface adjacent said contact surface extends outwardly beyond saidcontact surface, forming elevated side walls to contain said tubing andprevent lateral movement of said tubing along said contact surfaceduring operation.

In one embodiment, the side surfaces extend outwardly beyond saidcontact surface by 0.060 to 0.095 inches. In one embodiment, the sidesurfaces additionally extend inwardly along said contact surface by0.001 to 0.185 inches. In one embodiment, the side surfaces have thesame degree of concave curvature as said contact surface.

These, and other embodiments, are described in the Detailed Descriptionsection which should be read in light of the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will beappreciated, as they become better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings, wherein:

FIG. 1 is a front view of one embodiment of the dialysis system of thepresent invention;

FIG. 2 is a view of one embodiment of the dialysis system showing themodularity of the system;

FIG. 3 is a view of the front of one embodiment of the dialysis system,with the door open;

FIG. 4 is a top view of one embodiment of the portable dialysis systemwith exemplary dimensions denoted;

FIG. 5 is a front view of one embodiment of the portable dialysis systemwith exemplary dimensions denoted;

FIG. 6 is a front view of another embodiment of the dialysis system;

FIG. 7 is a view of another embodiment of the dialysis systemdemonstrating the modularity of the system;

FIG. 8 is a front view of another embodiment of the dialysis system;

FIG. 9 is a top view of one embodiment of the reservoir unit of thedialysis system;

FIG. 10 is a schematic view of exemplary components positioned on thetop surface of the reservoir unit of the dialysis system;

FIG. 11 is a schematic view of an exemplary attachment componentpositioned on the top surface of the reservoir unit of the dialysissystem;

FIG. 12 is a schematic view of exemplary components positioned on thetop surface of the reservoir unit of the dialysis system;

FIG. 13 is a schematic view of exemplary components positioned on thebottom surface of the controller unit of the dialysis system;

FIG. 14 is a schematic view of an exemplary interfacing componentpositioned on the top surface of the reservoir unit of the dialysissystem;

FIG. 15 is a schematic view of one embodiment of an internal frame ofthe controller unit of the dialysis system;

FIG. 16A is a front/side view of one embodiment of the dialysis systemof the present invention;

FIG. 16B is a front/side view of another embodiment of the dialysissystem of the present invention;

FIG. 16C is a side view of another embodiment of the dialysis system ofthe present invention;

FIG. 17A is a schematic view of an internal structure of one embodimentof the reservoir unit of the dialysis system of the present invention;

FIG. 17B is a schematic view of an internal structure of one embodimentof the reservoir unit of the dialysis system of the present invention;

FIG. 17C is a schematic view of an internal structure of one embodimentof the reservoir unit of the dialysis system of the present invention;

FIG. 17D is a circuit diagram of an exemplary conductivity sensor;

FIG. 17E is a diagram of an exemplary coil used in a conductivitysensor;

FIG. 18A is a schematic view of a flexure used in one embodiment of thereservoir unit of the dialysis system of the present invention;

FIG. 18B is a cross-section illustration of another embodiment of areservoir unit of the dialysis system;

FIG. 18C is an illustration of one embodiment of the electrical contactelements on the reservoir unit;

FIG. 18D is an illustration of one embodiment of the contact plate onthe external shell of the reservoir unit;

FIG. 18E is an oblique front view illustration of one embodiment of theinside of the bottom section of the dialysis system, depicting ahorizontal track for sliding the side protrusions of the reservoir unit;

FIG. 18F is an oblique front view illustration of one embodiment of aplastic ceiling frame positioned above a reservoir unit;

FIG. 18G is an illustration of one embodiment of the inside of thebottom section of the dialysis system, depicting contact elementstherewithin;

FIG. 18H is a front view illustration of one embodiment of a dialysismachine, depicting a flexure assembly and first and second framecomponents therein;

FIG. 18I is a side view illustration of one embodiment of the dialysismachine of FIG. 18G, depicting a flexure assembly and first and secondframe components therein;

FIG. 18J is a front view illustration of one embodiment of the reservoirunit installed within the bottom section of the dialysis machine;

FIG. 19 is a schematic view of a door locking mechanism implemented inone embodiment of the controller unit of the dialysis system of thepresent invention;

FIG. 20 is a schematic view of a door locking mechanism implemented inone embodiment of the controller unit of the dialysis system of thepresent invention;

FIG. 21 is a view of the front of one embodiment of the dialysis system,with the door open and a manifold installed;

FIG. 22 is a schematic view of one embodiment of moisture sensorspositioned on the reservoir unit of the dialysis system;

FIG. 23 is a close-up schematic view of one embodiment of moisturesensors positioned on the reservoir unit of the dialysis system;

FIG. 24 is a front view of one embodiment of the reservoir unit of thedialysis system with the door open;

FIG. 25 is a schematic view of one embodiment of a connector mechanismfor attaching a sorbent cartridge and/or concentrate jar to the dialysissystem;

FIG. 26 is a first exemplary fluid circuit diagram;

FIG. 27 is a second exemplary fluid circuit diagram;

FIG. 28 is a third exemplary fluid circuit diagram;

FIG. 29 is a fourth exemplary fluid circuit diagram;

FIG. 30 is a schematic view of one embodiment of an exemplary manifold;

FIG. 31 is a schematic view of another embodiment of an exemplarymanifold;

FIG. 32 is a schematic view of another embodiment of an exemplarymanifold with dimensions associated therewith;

FIG. 33 is a schematic view of another embodiment of an exemplarymanifold;

FIG. 34 is a diagram depicting a first exemplary fluid flow through aport;

FIG. 35A is a diagram depicting a second exemplary fluid flow through aport;

FIG. 35B is a diagram depicting a membrane structure over a port;

FIG. 36 is a diagram depicting one embodiment of an angled manifold portstructure;

FIG. 37 is a diagram of one embodiment of a molded fluid path having asubstantially planar base;

FIG. 38 is a fifth exemplary fluid circuit diagram;

FIG. 39 is a schematic of another embodiment of an exemplary manifoldused in association with other dialysis components;

FIG. 40 is a schematic of another embodiment of an exemplary manifold;

FIG. 41A is a front view of one embodiment of the controller unit of thedialysis system with the door open and manifold installed;

FIG. 41B is a side view illustration of one embodiment of a modifiedpump shoe with elevated side walls;

FIG. 41C is a contoured illustration of one embodiment of the modifiedpump shoe with elevated side walls of FIG. 41B;

FIG. 41D is an oblique side view illustration of another embodiment of amodified pump shoe with elevated side walls;

FIG. 41E is an oblique top down view illustration of multipleembodiments of modified pump shoes, each with elevated side walls ofvarying thickness based on the diameter of the pump tubing in use;

FIG. 41F is a cross-sectional illustration of the multiple embodimentsof modified pump shoes of FIG. 41E;

FIG. 41G is a side view illustration of one embodiment of the modifiedpump shoe with elevated side walls of FIG. 41B and a pump roller,depicting a length of tubing encompassed therebetween;

FIG. 42 is a front view of one embodiment of the controller unit of thedialysis system with the door open and manifold installed usingattachment guides;

FIG. 43 is a circuit diagram depicting an exemplary photo-acoustic flowmeter;

FIG. 44 depicts a plurality of propagating signals generated by theexemplary photo-acoustic flow meter;

FIG. 45 is a circuit diagram depicting an exemplary thermal flow meter;

FIG. 46 depicts a plurality of propagating signals generated by theexemplary thermal flow meter;

FIG. 47 depicts a plurality of variables defining the operation of anexemplary thermal flow meter;

FIG. 48 depicts a plurality of propagating signals generated by theexemplary thermal flow meter;

FIG. 49 depicts a plurality of variables defining the operation of anexemplary thermal flow meter;

FIG. 50A depicts a plurality of propagating signals generated by theexemplary thermal flow meter;

FIG. 50B depicts a plurality of propagating signals generated by theexemplary thermal flow meter;

FIG. 51 depicts a plurality of variables defining the operation of anexemplary thermal flow meter;

FIG. 52 depicts a plurality of variables defining the operation of anexemplary thermal flow meter;

FIG. 53 is a schematic diagram depicting an exemplary thermal flowmeter;

FIG. 54 is a schematic diagram depicting an exemplary thermal flowmeter;

FIG. 55 depicts a plurality of propagating signals generated by theexemplary thermal flow meter;

FIG. 56 is a front view of one embodiment of the controller unit of thedialysis system with the door open and manifold installed;

FIG. 57 is a diagram of an exemplary temperature probe;

FIG. 58 is a diagram of an exemplary disconnect monitoring system;

FIG. 59 is a diagram of an exemplary disconnect monitor;

FIG. 60 is a flowchart defining an exemplary disconnection detectionprocess;

FIG. 61 is a diagram showing an exemplary placement of a catheter tomeasure CVP;

FIG. 62 is a diagram showing an exemplary dialysis system using CVPmeasurements;

FIG. 63 is a diagram showing an exemplary placement of a catheter andmeasurement of CVP;

FIG. 64 is a sixth exemplary fluid circuit diagram;

FIG. 65 is a seventh exemplary fluid circuit diagram;

FIG. 66 is an eighth exemplary fluid circuit diagram;

FIG. 67 is a chart representing one embodiment of the use of pumpswapping to achieve volumetric accuracy;

FIG. 68 is a ninth exemplary fluid circuit diagram;

FIG. 69A is a tenth exemplary fluid circuit diagram;

FIG. 69B is an eleventh exemplary fluid circuit diagram;

FIG. 69C is a twelfth exemplary fluid circuit diagram;

FIG. 70 is a thirteenth exemplary fluid circuit diagram;

FIG. 71A is a first schematic view of an exemplary magnetic valvesystem;

FIG. 71B is a second schematic view of an exemplary magnetic valvesystem;

FIG. 72 is a schematic view of a component of an exemplary magneticvalve system;

FIG. 73 is a schematic view of another exemplary magnetic valve system;

FIG. 74 is a diagram depicting the operation of an exemplary magneticvalve system;

FIG. 75 is a chart relating diaphragm displacement to force for anexemplary magnetic valve system;

FIG. 76 is a diagram depicting the operation of an exemplary magneticvalve system;

FIG. 77 is a flowchart depicting the operation of an exemplary magneticvalve system;

FIG. 78 is a diagram of an exemplary hardware architecture for oneembodiment of the dialysis system;

FIG. 79 is a chart representing one embodiment of a plurality ofadditives for use in the dialysis system;

FIG. 80 is a flowchart depicting one embodiment of a process forenabling users to accurately add additives;

FIG. 81 is a schematic showing a packaged disposable kit;

FIG. 82 is a schematic showing one embodiment of a disposable kitcomprising a manifold and dialyzer attached to a plurality of tubes;

FIG. 83 is a schematic showing one embodiment of an electronic lock-outsystem integrated into disposables;

FIG. 84 is a fourteenth exemplary fluid circuit diagram;

FIG. 85 is a fifteenth exemplary fluid circuit diagram showing a primingmode of operation; and

FIG. 86 is a schematic of another embodiment of an exemplary manifold.

DETAILED DESCRIPTION

While the present invention may be embodied in many different forms, forthe purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

“Duration” and variations thereof refer to the time course of aprescribed treatment, from initiation to conclusion, whether thetreatment is concluded because the condition is resolved or thetreatment is suspended for any reason. Over the duration of treatment, aplurality of treatment periods may be prescribed during which one ormore prescribed stimuli are administered to the subject.

“Period” refers to the time over which a “dose” of stimulation isadministered to a subject as part of the prescribe treatment plan.

The term “and/or” means one or all of the listed elements or acombination of any two or more of the listed elements.

The terms “comprises” and variations thereof do not have a limitingmeaning where these terms appear in the description and claims.

Unless otherwise specified, “a”, “an”, “the”, “one or more”, and “atleast one” are used interchangeably and mean one or more than one.

For any method disclosed herein that includes discrete steps, the stepsmay be conducted in any feasible order. And, as appropriate, anycombination of two or more steps may be conducted simultaneously.

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.). Unless otherwise indicated, all numbersexpressing quantities of components, molecular weights, and so forthused in the specification and claims are to be understood as beingmodified in all instances by the term “about.” Accordingly, unlessotherwise indicated to the contrary, the numerical parameters set forthin the specification and claims are approximations that may varydepending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit thedoctrine of equivalents to the scope of the claims, each numericalparameter should at least be construed in light of the number ofreported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. All numerical values, however, inherently contain a rangenecessarily resulting from the standard deviation found in theirrespective testing measurements.

Device Structure

The present specification discloses embodiments of dialysis systems thatare modular and portable, with improved safety and functionality.Referring to FIGS. 1 and 2, in one embodiment, the dialysis system 100,200 comprises a top unit 101, 201 that is detachably affixed to a base102, 202. The base 102, 202 comprises a reservoir 122, 222 for fluidstorage, measurement, and monitoring. The top unit 101, 201, alsoreferred to as the main unit or controller unit, comprises a graphicaluser interface 114, 214, pumping unit, and a door 110, 210 with a powerlock and mechanical backup mechanism, as further discussed below.

To a first side of the top unit 101, 201 is a clasp 105 used todetachably affix a dialyzer 103. To a second, opposing side of the topunit 101, 201 is a sorbent cartridge locking base 104, 204 used todetachably affix a sorbent cartridge 107. It should be appreciated thatthe clasp 105, hemofilter 103, 315 sorbent cartridge locking base 104,318 and sorbent cartridge 107, 317 can be positioned on the same side ofthe top unit 101, as shown in FIG. 3. In either case, the bottom unithas a sufficiently larger area relative to the top unit such thatshelves are formed on either side of the top unit to hold the sorbentcartridge, to hold an infusate jar, to capture any spillage, and/or tochannel any leaks into a leak detector.

Between the dialyzer 103 and door 110 are anti-coagulant pumps in theform of syringe pumps 190. In one embodiment, the anti-coagulant syringepumps are heparin pumps with a flow range of 0-10 ml/hr adjustable by0.1 ml/hr increments. The pumps have an accuracy of +/−0.15 ml·hr or 15%of the flow set point depending on syringe accuracy. Optionally, the topunit 101 can comprise a bottle holder that has a spiked base to receivea bottle, top-down, within the bottle holder housing. Infusion lines areconnected to the inlet of the blood pump, outlet of the blood pump, oroutlet of the dialyzer (blood side). The infusion lines could also‘thread’ through air bubble detectors to sense if/when theanti-coagulant is emptied or blocked.

In one embodiment, referring to FIG. 4, the top unit 401, whichcomprises the user interface and controller, has the same depth, but adifferent length and height than the base unit 402, which comprises areservoir integrated with a scale. In this exemplary embodiment, boththe top unit 401 and bottom unit 402 have a depth D in the range of 10to 30 inches, more preferably approximately 19 inches. Referring now toFIGS. 4 and 5 simultaneously, in this exemplary embodiment, the top unit401, 501 has a length Lt in the range of 6 to 20 inches, more preferablyapproximately 14 inches, while the bottom unit 402, 502 has a length Lbin the range of 14 to 40 inches, more preferably 27 inches. In thisexemplary embodiment, the top unit 401, 501 has a height Ht in the rangeof 7 to 21 inches, more preferably approximately 14.5 inches, while thebottom 402, 502 unit has a height Hb in the range of 3 to 11 inches,more preferably 7 inches.

As shown in FIG. 5, the base unit 402, 502 may further be defined by twoshoulders 504, each extending outward, along the length of the base unit502, from the sides of a centrally positioned top unit 501. The top unitis preferably positioned in the center of the base unit 502, as measuredby length Lb in FIG. 4. Accordingly, the shoulder 504 can be defined ashaving a length in the range of 4 inches to 10 inches, more preferablyapproximately 7 inches. Extending upward from the surface of the baseunit 502, where shoulders 504 physically meet top unit 501, is a lip 503that defines a surface upon which top unit 501 is aligned and placed.The lip 503 is contiguous around the base of the top unit 501, havingthe same length and depth as the top unit 501, with a height defined asthe difference between Ht2 and Ht. In one embodiment, the lip height isin the range of 0.1 to 3.5 inches, more preferably 0.6 inches. Theoverall height of the system, Ht3, is in the range of 10 to 35 inches,more preferably 22 inches.

The external housing structures defining the top unit 501 and base unit502 may be characterized as rectangular parallelepipeds, cuboids, orboxes, each with four sides, a top, and a bottom. In an exemplaryembodiment, for both the top unit 501 and base unit 502, two of the foursides, each having an exterior and interior surface, have the sameheight, length, and depth, while the top and bottom structures, eachhaving an exterior and interior surface, have the same height, length,and depth.

It should be appreciated that the system configurations shown in FIGS.1, 2, 3, 4, and 5 are exemplary and not limiting. For example, shown inFIG. 3, the top unit 301 may be positioned on one side of the base unit302 (creating an asymmetric base), as opposed to being centrallypositioned on top of the base unit 302 relative to the overall length ofthe base unit 302 (creating a symmetric base). While placement of thetop unit 301 to one side of the base unit 302 has the advantage ofplacing all tubing connections and consumables on the same side of thesystem, sorbent cartridge 317 and dialyzer 313 are unnecessarily crowdedtogether, making the machine more difficult to use.

Referring to FIG. 6, in another embodiment, the top unit 601, whichcomprises the user interface and controller, has the same depth andlength, but a different height than the base unit 602, which comprises areservoir integrated with a scale 604. In this exemplary embodiment,both the top unit 601 and bottom unit 602 have a depth in the range of16.0 to 20.0 inches, more preferably less than 24 inches andapproximately 17.0 inches. In this exemplary embodiment, the top unit601 and bottom unit 602 have a length Lt in the range of 10.0 to 15.0inches, more preferably less than 18 inches or approximately 13.0inches. In this exemplary embodiment, the top unit 601 has a height Htin the range of 10.0 to 14.0 inches, more preferably less than 17 inchesand approximately 12.0 inches, while the bottom unit 602 has a height Hbin the range of 9.0 to 11.0 inches, more preferably less than 13 inchesand approximately 9.5 inches. The total height of both units together isdenoted by Ht3. The base unit 602 and top unit 601 therefore have thesame footprint, although different heights. It should be appreciatedthat the base unit 602 and top unit 601 could have the same footprintand same height as well.

Extending out from under the base unit 602 are flattened lateral wings610 which comprise connectors for attaching the sorbent cartridge andinfusate container 615. The surface of the lateral wings 610 maycomprise a membrane that can electronically sense the presence ofmoisture and/or may be angled to direct any moisture to strategicallyplaced sensors.

Referring to FIG. 7, in another embodiment, the top unit 701 mayphysically interface with a docking station 705, which electronicallyand fluidically interfaces 715 with a remotely located base unit 702.While the reservoir located in the base unit 702 would still have to bein fluid communication with the controller 701, the use of a dockingstation 705 would allow for greater flexibility in switching out thesize of the reservoir system being used, thereby allowing one controllerdesign to be implemented under multiple use scenarios or for a widerrange of patients, e.g. small vs. large patients.

Referring to FIG. 8, in yet another embodiment, the portable dialysissystem 800 incorporates an upper subsystem (pumping and control unit)801, as previously described, with a lower assembly 802. The lowerportion 802 of the system 800 comprises an independent, suspended bag ofdialysate 805. That is, the dialysate bag 805 is not incorporated as apart of the lower assembly 802, as in the previously disclosedembodiments. Further, the lower assembly 802 is designed such that itincorporates a weighing mechanism integrated into the structures 810that suspend the independent bags of dialysate 805. This arrangement issuitable when the dialysis system is configured to operate inhemofiltration mode because, in the hemofiltration mode, various sensorsused in sorbent based dialysis, such as ammonia, pH and sodium sensors,are not required; therefore the entire reservoir assembly module can beremoved, and the system 800 can simply be operated using a bag ofdialysate 805. The modular and compact design of the lower subsystem 802makes its removal easy, and simplifies the system operating inhemofiltration mode by taking away the unnecessary components. This isanother advantage of integrating the major components of the dialysatecircuit used during hemodialysis mode into a lower base unit 802.

The dialysis system of the present invention achieves functional andoperational parameters that represent a substantial improvement over theprior art. Referring to the embodiments shown in FIGS. 1 through 6, thetop unit is in the range of approximately 20-40 pounds, and moreparticularly 30 pounds, and the bottom unit is in the range ofapproximately 15-30 pounds, and more particularly 22 pounds, therebyweighing less than prior art systems. The top unit is in the range ofapproximately 1 to 4 cubic feet, and more particularly 2.3 cubic feet,and the bottom unit is in the range of approximately 1 to 4 cubic feet,and more particularly 2.8 cubic feet, thereby having a smaller volumethan prior art systems.

Furthermore, the dialysis system uses less water than prior art systems.While conventional systems use approximately 120 liters per treatment,in one embodiment, the present system uses between 3 and 8 liters, andmore particularly between 5 and 6 liters. Furthermore, the system doesnot require a home drain, supply connection, or separate outlet toaddress excess water. The system uses potable water that meets the EPAstandard for drinkable water, requiring no additional purification.

Additionally, the system design is more compact, with low powerrequirements (only 300 at peak and 50 to 100 W during operation), noseparate fluid bags required for priming or travel, and integratedpumps. The system operates from AC line power with a voltage of 100 to240 VAC, a frequency of 50/60 Hz and leakage current class CF. In oneembodiment, power failure is indicated by an audible alarm and thesystem is capable of providing for itself backup power sufficient to runfor 15 minutes following the power loss.

In one embodiment, the system is designed to operate in an environmentwith an ambient temperature of 15-35° C., an ambient humidity of 30-90%non-condensing, and an ambient pressure of 520-780 mm Hg. In oneembodiment, the system is designed to be drip proof as per IngressProtection Code (IPC) 1 of the International Electrotechnical Commission(IEC) standard 60529. In one embodiment, the system, without dialyzer,is designed to be stored in an environment with an ambient temperatureof −20-70° C. with non-condensing humidity. In one embodiment, thesystem with attached dialyzer is designed to be stored in an environmentwith an ambient temperature of 5-30° C. (41-86° F.) until used.

The device operates using a blood flow range of 20-600 Qb (ml/min), adialysate flow of 50-500 Qd (ml/min). The volumetric accuracy is alsoprecise at less than +/−30 ml/hr. In one embodiment, the blood flow rateis adjustable by 10 ml/min increments and the accuracy is +/−10% at aset flow point of 200 ml/min. The inlet pressure for the blood flowsystem is −50 mm Hg and the outlet pressure is 50 mm Hg using water at37° C. In one embodiment, dialysate flow rate is adjustable by 50 ml/minincrements and the accuracy is +/−25 ml/min or 10%. The maximum outputpressure of the dialysis flow system is 1900 mm Hg at a flow rate of 500ml/min. In one embodiment, ultrafiltration can be set to 0 or a rate of50-2500 ml/hr. Accuracy is set to +/−100 g or +/−30 g every hour,whichever is greater. In one embodiment, ultrafiltration is not toexceed 25% of the blood flow rate and is intended to be used in limitedduration.

In one embodiment, dialysate temperature control is set to maintain thedialysate temperature at a range of 35-39° C. with an accuracy of+/−0.5° C. of the set point measured at the inlet of the dialyzer. Inone embodiment, dialysis is stopped if the dialysate temperature risesabove 42.0° C.

In one embodiment, the system is capable of detecting the presence of anindividual bolus of air >1 ml at all operating pressures and a series ofmicro-bubbles of air that total 1.5 ml in 30 seconds. In one embodiment,the system is capable of detecting a blood leak and includes audible andvisual alarms to notify users of a blood leak. In one embodiment, thehigh alarm limit is set to be not more than 0.35 ml/min of blood lossfor a fixed alarm tested at 25% hematocrit.

As shown in FIG. 2, the dialysis system is modular. In one embodiment,the top unit 201 can be physically separated from the bottom unit 202.The top unit 201 contains the primary electronics of the system,including the graphical user interface, controllers, and pumps,integrally formed into a self-contained housing. The larger, bulkierbottom unit 202 contains the reservoir 222. Separation of the systemelectronics from the reservoir allows the portable dialysis system to beseparated into multiple units for installation, service, and travel,with each subunit being easily handled, packaged and carried. The designspecifically sizes components for shipping via UPS or other door to doorcarriers. It further provides flexibility in product growth. Forexample, if improvements are made to the controller unit or, separately,to the reservoir (such as reducing fluid volume or a change in volumescale measurement), an existing customer need only upgrade one of thetwo component parts, not both. Similarly, if only one of the twocomponents breaks (e.g. the pump burns out), a customer need only sendin one for repair or purchase one of the two components.

To enable the above described modularity, embodiments of the presentinvention employ a latching mechanism that, in a first configuration,securely attaches the bottom unit 202 to the top unit 201 and can bemanipulated to removably detach the bottom unit 202 from the top unit201. Even though the two systems could be simply stacked atop eachother, without a latch, the presence and use of a latch reduces thelikelihood of an accidental disconnection. Furthermore, when latchedtogether the device is easier to move. The latch mechanism preferablyuses no tools and is simply achieved using male/female matingconnections present on the base of the top unit and top surface of thebottom unit. Further preferably, the latch mechanism is designed toensure solid alignment between the top and bottom units, therebyenabling the use of electronic components (such as exposed electronicconnectors on the bottom of the top unit and top of the bottom unit asfurther described below) which, when the units are properly aligned,automatically come into contact and complete a power circuit. Thispermits the use of a single power supply and simpleconnection/disconnection.

Referring to FIG. 9, the bottom unit 902 has four sides 905 a, 905 b,905 c, 905 d, a base, a top surface 906, and a reservoir 922 accessiblevia first side 905 d. The bottom unit 902 further comprises a pluralityof latch mating structures 920 a, 920 b on its top surface 906. In oneembodiment, the present invention comprises two latch mating structures920 a, 920 b that, relative to the length of the bottom unit 902, arecentrally positioned to ensure even weight distribution. The first latchmating structure 920 a is preferably positioned a distance equal to onethird of the width of the bottom unit 902, as measured from side 905 d.The second latch mating structure 920 b is preferably positioned adistance equal to one third of the width of the bottom unit 902, asmeasured from side 905 b.

The latching mechanisms, as shown in FIG. 10, comprise a metal frame1001 that is securely fastened using, for example, a bolt, screw, orother fastener 1002, to the top surface of the bottom unit 1005. Theframe 1001 supports a protrusion or elongated member 1003 that canflexibly insert into, and be removed from, a corresponding latch.

To securely and removably attach the bottom unit to the top unit, thetop unit comprises complementary mechanical sliding latches, which aresecurely attached to the base of the top unit. In one embodiment, thebase of the top unit comprises a first latch that is preferablypositioned in the center of top unit, relative to the length of the topunit, and a distance equal to one third of the width of the top unit, asmeasured from a first side. The base also comprises a second latch thatis preferably positioned in the center of top unit, relative to thelength of the top unit, and a distance equal to one third of the widthof the top unit, as measured from a second side, which is opposite andparallel to the first side.

As shown in FIG. 11, the top unit comprises a latch 1100 with a slidingmetal flat base 1120. Rails 1130 are slidably engaged with the bottomsurface of the top unit, which has mating members to hold the rails 1130in place. The latch 1100 has two latching tabs 1115 which are adapted toslide into, and out of, mating structures physically attached to the topsurface of the base unit.

Latches 1100, attached to the top unit, mate with latch matingstructures 920 a, 920 b on the top surface of the bottom unit 906. Inoperation, when the sliding latch 1100 is in a first position, the topunit will not effectively fit on top of, or align with, the base unitbecause the sliding latch 1100 will not properly physically mate withlatch mating structures 920 a, 920 b. To prepare the top unit for secureplacement on to the top surface of the base unit 906, the slidinglatches are moved within the member holding structure positioned on thebottom of the top unit and placed into a second position. In the secondposition, the handle of the latch 1111 will protrude, thereby moving thetabs 1115 away from the latch mating structures 920 a, 920 b andallowing the top unit to sit correctly on the base unit.

Referring to FIGS. 12 and 13, the top unit 1301, which has slidinglatches 1380, is aligned to the bottom unit 1202 by four small rubberfeet, or footing pads, 1340 on the bottom of the top unit 1301, whichare configured or adapted to snugly and securely fit into four cavitiesor pockets 1230 located proximate to each corner on the top of thebottom unit 1202. Additionally, the top unit 1301 can be accuratelyaligned to the bottom unit 1202 using alignment pins 1260, orprotrusions, on the top surface of the base unit 1202, which areconfigured or adapted to securely and snugly fit into correspondingcavities 1390 on the bottom surface of the top unit 1301. The bottomunit also has latch mating structures 1263, as described above.

Aligning the rubber footings 1340 into the cavities 1230 and the pins1260 into the cavities 1390 ensures that latches 1380 on the top unit1301 can be readily aligned and latched to the latch matching structures1263 without excessive trial and error. Once aligned, the latch 1380 ismated with the latch mating structures 1263 by sliding the latches 1380into the latch mating structures 1263, thereby creating a tight fitbetween the two units. Referring back to FIGS. 9 and 11, to unlatch,latch handles 1111 are pulled or otherwise manipulated, therebyreleasing tabs 1115 from the base unit slots 920 a, 920 b, and allowingthe top, upper unit to be lifted from the bottom, lower unit.

Furthermore, to enable the above described modularity, embodiments ofthe present invention also employ an electrical and communicationconnection mechanism that, in a first configuration, securelyestablishes electrical communication and/or data communicationconnection between the bottom unit and the top unit and, in a secondconfiguration, terminates an electrical communication and/or datacommunication connection between the bottom unit to the top unit.

Referring to FIG. 14, the electrical connections between the top andbottom units are created when the top unit is placed on the bottom unit.These connections are made through a non-contact infrared communicationsport 1403 and a push-pin power port 1404, which are integrally formedinto plates 1402 and securely attached using fasteners 1401 to the topsurface of the bottom unit 1405. It should be appreciated that thebottom surface of the top unit would then comprise, in proper alignmentwith the push-pins, an electrical contact pad. It should further beappreciated that the location of the push-pins and contact pads can bereversed, thereby placing the push-pins on the bottom surface of the topunit and the contact pad on the top surface of the bottom unit.

In one embodiment, a high current power connection is created by placingsix spring loaded pins into electrical contact with contact pads, whichare integrated into the bottom surface of the top unit. Three pins arefor +24 volt DC current and three pins are for ground. In oneembodiment, the pins or probes have the following characteristics: a)minimum center of 0.175 inches, b) current rating of 15 amps(continuous), c) spring force in the range of 6.2 oz to 9.0 oz at 0.06inches to 0.067 inches of travel, d) typical resistance of less than 10mΩ, e) maximum travel in the range of 0.09 to 0.1 inches, f) workingtravel in the range of 0.06 to 0.067 inches, g) barrel made ofnickel/silver and gold plated, h) stainless steel spring (optionallygold plated), i) plunger made of full-hard beryllium copper and goldplated, and j) optionally a stainless steel bias ball. The spring forceof the pins assists in preventing breakage by absorbing bending or othercontortions. It should be appreciated that the term electrical pinsrepresents any protrusion capable of transmitting electrical power andelectrical contact pad represents any surface capable of receiving anelectrical pin.

The non-contact infrared communication port 1403 employs two LEDtransmitters and two LED receivers which align to, and communicate with,two LED transmitters and two LED receivers on the bottom surface of thetop unit. The distance between the transmit and receive ports is lessthan 0.3 inches. On both the top surface of the bottom unit and bottomsurface of the top unit, the four LED units are divided into two pairs,a control pair (comprising one transmitter and one receiver) and onesafety pair (comprising one transmitter and one receiver). These portsare placed in data communication when the top and bottom units areproperly aligned.

In one embodiment, the LED transmitters are high speed infrared emittingdiodes, 870 nm, made of GaAlAs double hetero technology. The LEDtransmitters are high speed diodes having the following characteristics:a) extra high radiant power, b) low forward voltage, c) suitable forhigh pulse current operation, d) angle of half intensity ofapproximately 17 degrees, e) peak wavelength of approximately 870 nm, f)reverse voltage of approximately 5 V, g) forward current ofapproximately 100 mA, h) a peak forward current of approximately 200 mA,i) surge forward current of approximately 0.8 A, j) power dissipation ofapproximately 190 mW) junction temperature of approximately 100 degreesCelsius, and 1) an operating temperature range of −40 to 85 degreesCelsius. It should be appreciated that the non-contact infraredcommunication ports can be distributed in any functional manner acrossthe top surface of the bottom unit or bottom surface of the top unit. Itshould be further appreciated that any other communication port orstructure known to persons of ordinary skill in the art can beimplemented herein.

In one embodiment, the LED receivers are high speed silicon photodiodeswith extra fast response times, radiant sensitive area of approximately0.25 mm² and an angle of half sensitivity of approximately 15 degrees.The receivers have the following characteristics: a) reverse voltage ofapproximately 60 V, b) power dissipation of approximately 75 mW, c)junction temperature of approximately 100 degrees Celsius, d) anoperating temperature range of −40 to 85 degrees Celsius, e) forwardvoltage of approximately 1 V, f) minimum breakdown voltage of 60 V, andg) diode capacitance of approximately 1.8 pF.

Referring back to FIGS. 1, 2 and 3, atop the controller unit 201 arehandles 211, 311 and a workspace in the form of a useable shelf 112,212. The handles, located on the upper pumping portion of the system,are directly connected to the internal structure or frame of the systemand are not simply an extension of the exterior plastic molding,housing, or skins surrounding the top unit 101, 201. The directconnection to the internal frame of the system permits using the handleto reposition the system in a manner that is safe and can reliablyhandle the load, particularly when the instrument is in operation withsix liters of water (adding approximately 40 lbs).

Referring to FIG. 15, in one embodiment, the top unit 1501 comprises aninternal metal casing, frame or housing 1510 within which, and to which,the electronics, controller, and other top unit components arecontained. The internal casing 1510 comprises a horizontal protrudingarm 1507 that extends to the back side of the top unit 1501. Thesubstantially horizontal top shelf 1505 comprises at least one handle1520 that is integrally formed into the top shelf structure 1505, a basebracket 1530, and a vertical arm 1506, thereby creating a single,contiguous metal or molded plastic piece. The base bracket 1530 issecurely attached to the internal casing 1510 at the front of the topunit 1501 and the vertical arm 1506 is securely attached to theprotruding arm 1507 at point 1508 using screws. By securely attachingthe shelf 1505 and handle 1520 structure to the internal casing 1510 ofthe top unit 1501, one avoids potential damage or breakage that wouldnormally occur by placing large weight loads at the point of connectionbetween a handle and an external or outside housing of the top unit.

Also attached to the internal frame or casing 1510 is a metal door 1562,with hinges 1565, which forms the internal frame of door 110, shown inFIG. 1. Door 1562 is securely attached to plate 1561 which is part ofinternal frame 1510. Structures 1563 and 1572 are structures that hold,and/or represent protrusions of, the internal motors and pulleyassemblies. Protrusion 1583, which extends from the back of frame 1510,is used to connect various electronic components, including a powerentry module and USB connections 1582. The top of the controller unit,or shelf 1505, is flat and has side-walls making it ideal for storage ofsupplies or a temporary working surface.

Another structural feature of the controller unit 1601 is shown in FIG.16A. Preferably, the unit 1601 has a built-in exposed reader, such as abar code reader or RFID tag reader 1605, which can be used to read codesor tags on the disposable components. Operationally, a user wouldpreferably swipe all of the codes/tags on the disposable components bythe reader. Prompting the user can be effectuated through an initial GUIdialysis setup step which instructs the user to swipe each disposablecomponent past the reader.

Upon doing so, the reader obtains identifying information about thedisposable, transmits that identifying information to an internal tablestored in memory, compares the identifying information to the contentsof the internal table, and verifies (or does not verify) that thecorrect disposable components (particularly additives used in thedialysate) are present. The contents of the internal table can begenerated by manual input of the identity and amount of the disposablesor by remote access to a prescription that details the identity andamount of the disposables. This verification step has at least twobenefits. The first is to ensure that the user has, in his or herpossession, all of the required components and the second is to ensurethat the correct components are being used (not counterfeit orunsuitable disposables). This component can be used to enable a varietyof user interfaces, as further described below.

In another embodiment, the reader 1605 mounted on the side of the topunit is a specialized multi-function infrared camera that, in one mode,provides the ability to read bar codes and, in another mode, detects alevel change in the infusate container. The camera emits an infraredsignal that reflects off fluid level. The reflected signal is receivedby the camera's infrared receiver and processed, using a processor, todetermine the location of the meniscus of the fluid level. In oneembodiment, the camera can determine and monitor a change in the fluidlevel to a resolution of 0.02 mm. In one embodiment, the camera is a 1.3megapixel single-chip camera module with one or more of the followingcharacteristics: a) 1280 W×1024 H active pixels, b) 3.0 μm pixel size,c) ⅓ inch optical format, d) RGB Bayer color filter array, e) integrated10-bit ADC, f) integrated digital image processing functions includingdefect correction, lens shading correction, image scaling, demosaicing,sharpening, gamma correction, and color space conversion, g) embeddedcamera controller for automatic exposure control, automatic whitebalance control, and back level compensation, h) programmable frame rateand output derating functions, i) up to 15 fps SXGA progressive scan, j)low power 30 fps VGA progressive scan, k) 8-bit parallel videointerface, l) two-wire serial control interface, m) on-chip PLL, n)analog power supply from 2.4 to 3.0 V, o) separate I/O power supply, p)integrated power management with power switch, and q) 24 pin shieldsocket options. In one embodiment, the camera is a 1.3 megapixel cameramade by ST Microelectronics, Model No. VL6624/VS6624.

The top or bottom unit of the dialysis system also preferably haselectronic interfaces, such as Ethernet connections or USB ports, toenable a direct connection to a network, thereby facilitating remoteprescription verification, compliance vigilance, and other remoteservicing operations. The USB ports permit direct connection toaccessory products such as blood pressure monitors orhematocrit/saturation monitors. The interfaces are electronicallyisolated, thereby ensuring patient safety regardless of the quality ofthe interfacing device.

The front of the top unit has a graphical user interface 114 thatprovides for a simple user interface with the system 100. In a homesetting, it is important that the device be easy to use. Maximal use ofcolors and the touch screen is ideally suited for the application. Thetouch screen allows multiple user input configurations, providesmultiple language capability, and can be readily seen at night(particularly with brightness controls and night-vision colors). In oneembodiment, the screen is at least 10″ measured diagonally with aresolution of 800×600 pixels. In one embodiment, the screen uses a textof 17 pt and unique colors to display alarms.

The GUI further includes a feature for the automatic closing, opening,and locking of the door during operation. In one embodiment, the GUIopens the door to a first latch position and then a user must press aphysical door-open button to fully open the door. In another embodiment,the device has a manual override which permits the user to open the door(e.g. by pressing the open door button twice or with extra force) tomanually open the door. Referring to FIG. 16A, preferably, proximate tothe GUI 1630, is a single mechanical button 1610, with lighted visualindication, that, if activated, provides a central stop button with acommon function (such as stopping the system) regardless of the state ofoperation.

To provide further security and safety, the system 1600 controls theopening of the reservoir door 1625 in the base unit 1615 withoutrequiring a door controller, button, or mechanical system that isindependent from the door control system of the top unit 1601. In oneembodiment, the reservoir door 1625 is physically blocked from openingby a protrusion 1620 that is physically attached to, connected to, orotherwise controlled by the front door 1635 of the top unit 1601. Theprotrusion 1620, which can extend over the reservoir door 1625 from anydirection relative to the top unit 1601, serves to provide a physicalbarrier to opening the reservoir door 1625. Therefore, in thisembodiment, one cannot open the reservoir door 1625 without firstunlocking and opening the controller door 1635, which is controlled bythe user interface.

In another view of one embodiment of the dialysis system, shown in FIG.16B, the dialysis system 1600 comprises a controller unit 1601 with anammonia sensor 1670, GUI 1630, and a single mechanical button 1610 foropening and closing the controller door 1635, and a base unit 1615 witha reservoir door 1625 that is physically blocked from opening by aprotrusion 1620 that is physically attached to, connected to, orotherwise controlled by the front door 1635 of the top unit 1601 andbuilt-in exposed reader, such as a bar code reader or RFID tag reader1605. The controller unit 1601 and base unit 1615 are positioned atop asingle continuous substantially planar base or partitioned planar base1645 that has two attachment mechanisms 1675, 1695. The first attachmentmechanism 1675, which is used to hold in place a sorbent cartridge 1680,is positioned adjacent to the second attachment mechanism 1695, which isused to hold in place a concentrate jar 1695, on the same side of thedialysis system 1600. The planar base 1645 preferably comprises a driptray or other moisture catching or sensing surface.

Referring to FIG. 16C, the controller unit 1601 and base unit 1615 areshown in profile. The sorbent cartridge 1680 is held in place byattachment mechanism 1675 and concentrate jar 1690 is held in place byattachment mechanism 1695. Both the sorbent cartridge 1680 andconcentrate jar 1690 are placed atop a planar surface, such as a driptray 1668, to insure all moisture is captured. Scanner 1605 ispositioned on the side of the base unit 1615 and in direct opticalcommunication with the concentrate jar 1690. Fluids flow from the system1600 to and from the sorbent cartridge 1680 and from the concentrate jar1690 via three tubular or fluid segments 1641, 1642, 1643. Tube segment1642 places the concentrate jar 1690 in fluid communication with themanifold through the concentrate manifold port. Tube segment 1641 placesthe sorbent cartridge 1680 in fluid communication with the manifoldthrough the sorbent outflow port, thereby sending dialysate requiringregeneration to the sorbent cartridge 1680. Tube segment 1643 places thesorbent cartridge 1680 in fluid communication with the manifold throughthe sorbent inflow port, thereby receiving regenerated dialysate fromthe sorbent cartridge 1680. The tube segment 1643 is removably attachedproximal to the ammonia sensor 1670 using mechanisms 1671 such as hooks,clips, clamps, or other means permitting a tube segment 1643 to beeasily removed and placed in proximal contact with the ammonia sensor1670 positioned on the side of the controller unit 1601 on the same sideas the sorbent cartridge 1680. In one embodiment, the ammonia sensor1670 comprises an optical sensor that uses a colorimetric measurementapproach to determining the presence of ammonia and whether such ammoniaexceeds a predefined threshold.

Referring to FIG. 1, the reservoir system 102 has a door 118 which, whenpulled and not blocked by any protrusion, slides the reservoir 122 out,or otherwise makes the reservoir 122 accessible to a user, to allow auser to insert or change fluids used for dialysis. The reservoir volumeis monitored by a scale system. The scale-based fluid balance 604,depicted in FIG. 6 and more particularly in FIGS. 17A and 17B, isintegrally formed with the reservoir and provides accurate fluid removaldata and enables accurate balance calculations, thereby preventinghypotension and other ailments caused from fluid imbalances. Integratingthe scale with the reservoir and enclosing them completely provides fora more robust system.

Referring to FIG. 17A, the internal structure 1700 of the reservoirsystem is shown. A metallic internal frame 1720 comprises two sides1721, a back 1722, an open faced front 1723, and a base 1724. Theinternal structure or frame is shown without the external housing, asdepicted as element 102 in FIG. 1. A scale 1718 is integrated into thereservoir internal structure 1700. The bottom surface 1715 of the scale1718 comprises a metal surface or pan that, together with the rest ofthe scale 1718, is suspended from the external reservoir housing (shownas 102 in FIG. 1) by four flexures 1705. Below the bottom surface 1715of the scale is preferably situated a heating pad, such as a square,rectangular, circular, or other shaped surface capable of incurring atemperature increase and conducting the increased temperature, as heat,to surface 1715. A conductivity coil 1770, capable of exerting a fieldand using changes in that field to measure conductivity, is integratedinto base surface 1715. Accordingly, when a reservoir bag (not shown) isplaced on bottom surface 1715, it can be heated by a heating pad and,because it is in contact with coil 1770, its conductivity can bemonitored.

The internal surfaces of the sides 1721 comprise a plurality of rails,elongated members, or protrusions 1719 that serve to secure, hold,encase or attach to a disposable reservoir bag mounting surface, such asa plastic sheet, 1710 to which a reservoir bag can be attached.Specifically, a reservoir bag positioned on surface 1715 can have anoutlet attached to conduit 1771 integrated into sheet 1710. Mounted ineach of the four corners of the scale surface 1718 are flexures 1705with each one comprising a hall sensor and magnet.

Accordingly, in one embodiment, components of the reservoir subsystemassembly include, but are not limited to a dialysate reservoir,including disposable reservoir liner or bag, dialysate heater, dialysatetemperature monitor, reservoir weighing system, including magneticflexures and tilt sensor, dialysate ammonia concentration and pH sensor,including disposable sensor elements and reusable optical reader,dialysate conductivity sensor (non contact type), and wetness or leaksensors.

One of ordinary skill in the art would appreciate that apart from thesensors listed above other components in the dialysate circuit, such aspumps and sensors such as pressure transducers may also be includedwithin the reservoir module. Further, various sensors such as ammoniaand pH sensors may be integrated as individual sensors into thereservoir module, or as a single ‘sensor sub-module’ that comprises allthe sensors.

The inclusion of each of these components is designed in a manner thatmakes the reservoir assembly module specially suited for use in theoperation of a recirculating sorbent based dialysis system. Further, themodule is also designed such that during other forms of dialysis, suchas single pass hemofiltration, any unnecessary elements of the modulethat are specific only to sorbent based dialysis can be removed.

FIG. 17B illustrates one embodiment of the reservoir assembly module,with the outer skins or covers rendered transparent, thereby revealingthe internal arrangement. An opening 1741 is provided in the front ofthe reservoir subsystem module 1700. The main function of the reservoirsubassembly is containment of the dialysate. The opening 1741 allows adisposable reservoir bag, which can be a conventional IV bag withdialysate contained therein, to be inserted. The reservoir module 1700is also provided with a pan 1742 inside the front opening for containingthe reservoir bag. In one embodiment, a flat film heater and temperaturesensor are both located underneath the bottom of the reservoir pan 1742,and help maintain the temperature of dialysate fluid at body temperatureor close to it. In one embodiment, the temperature of the dialysatefluid can be set by the user.

In one embodiment, the reservoir pan 1742 is suspended in a scalemechanism 1743, as further described below. The scale mechanism 1743 canbe used for accurate measurement of the weight of the dialysate fluid inthe reservoir bag prior to start of the dialysis, and for maintainingvolumetric balance of the dialysate fluid in the circuit duringdialysis.

On the top of reservoir assembly module 1700, features 1744 forattachment to the pumping unit of the dialysis system are provided, aspreviously discussed. These features help in easy coupling and removalof the reservoir assembly module from the pumping unit, which in oneembodiment may be mounted on the top of the reservoir assembly. Asfurther discussed below, the top of the reservoir assembly module isalso equipped with drain gutters 1745 on either side of the module.Individual wetness sensors (not shown) are provided in each of thegutters. As known in the art, wetness sensors are optical devices thatsense moisture on account of increased coupling of light into fluid asopposed to air, by virtue of the difference of index of refractionbetween air and fluid. The wetness sensors in the drain gutters 1745keep track of moisture and indicate any leaks in the pumping system whenit is mounted on top of the reservoir assembly. By having a separatewetness sensor in the drain gutter on either side, leaks can belocalized and specific guidance given to the user regarding anycorrections that may be required.

FIG. 17C illustrates another view of the reservoir assembly module,wherein the outer covers of the module 1700 are totally removed and someinternal components rendered transparent. Referring to FIG. 17C, thereservoir pan 1752 is provided with an internal gutter 1753. The gutter1753 is further equipped with a wetness sensor, which is located justunder the dialysate pan 1752, to which flexures are attached 1755, sothat it can sense a leak inside the reservoir assembly 1700.

The reservoir assembly module 1700 further comprises a sensor pod 1754or sub-module, which comprises a collection of various sensors on thesame circuit board. The sensor board comprises sensors specificallyrelated to sorbent based dialysis, such as ammonia and pH sensors. Inone embodiment, the ammonia sensor comprises disposable color sensitivestrips, which are made up of a material that exhibits a visible changein color in response to the level of ammonia present in the dialysate.For example, the color of the indicator strip may change gradually fromblue to yellow, depending on the ammonia level present around thatstrip. Such visual color indication makes it easier to keep track ofammonia levels and to identify if ammonia breakthrough occurs. In oneembodiment, for a more precise assessment of color change in ammoniaindicator strips, an optical sensor is used. The optical sensor is alsolocated in the sensor module 1754, and can be used for converting thegeneral visible color reading into an accurate indication of ammonialevel.

With respect to the dialysate sodium concentration, it should beappreciated that, to perform kidney dialysis properly and cause correctdiffusion across the dialyzer, the concentration of sodium must bemaintained within a certain range. A conventional method of determiningthe sodium concentration of a fluid is to measure the fluid's electricalconductivity and the fluid's temperature and then calculate theapproximate sodium concentration. An improved method and system formeasuring sodium concentration in dialysate in a non-contact manner usesa non contact conductivity sensor built in to the bottom of thereservoir pan 1752.

In one embodiment, the non-contact conductivity sensor is an inductivedevice utilizing a coil. Change in sodium concentration changes theconductivity of the dialysate solution, which in turn changes theimpedance of the coil. By placing the conductivity sensor in the bottomof the reservoir pan 1752, and thus under the dialysate bag in thereservoir, a large surface area is presented to the coil. This ensureshigh accuracy of measurement, in addition to requiring no physicalcontact of the sensor with the dialysate fluid.

Referring to FIGS. 17D and 17E, components of a non-contact electricalconductivity sensor are shown, including a coil 1788 with n-turnsdefining the generation of a magnetic field when properly energized anda diagram of the resulting resonant LCR tank circuit 1780 created whenthe coil, defined by resistance elements Rs 1786 and Rp 1785 andinductor element L 1787, is electrically coupled with a capacitor 1781.

The coil 1788 is a multi-layer, circular, flat coil used as an energystorage device in conjunction with a capacitor 1781. The coil 1788 hasloss elements, which comprises the electrical resistance of the coilwire Rs 1786 and a magnetic field loss element Rp 1785, the electricalconductivity of the fluid in the bag.

The coil 1788 diameter is a function of magnetic field penetration intothe fluid. Another factor for fluid penetration is operating frequency.Low operating frequency will penetrate deeper into the fluid, but with acost of lower losses. A larger coil will have small effect cause bydimensional tolerances. A defining equation is provided below:

$L = {\frac{0.31({aN})^{2}}{{6a} + {9h} + {10b}}({\mu H})}$

Where a=average radius of the coil in centimeters, N=number of turns,b=winding thickness in centimeters, h=winding height in centimeters. Inone embodiment, the radius of the coil is in the range of 2 to 6 inchesand, more particularly, 2, 3, 4, 5, and 6 inches and all increments inbetween.

Referring to the circuit 1780, the physical coil 1788 is represented byL 1787 and Rs 1786, with L being the inductance of the coil and Rs beingthe electrical resistance of the coil wire. Energy loss of the magneticfield produced by L 1787 is represented by Rp 1785. Energy loss Rparises from, and is directly related to, the conductivity fluid which isproximate to the coil 1788. Therefore, if the coil 1788 is placed in thereservoir pan, integrated into the surface of the reservoir pan, orotherwise placed at a distance such that the magnetic field generated bythe coil 1788 can be affected by the presence of dialysate within a bag,or, more particularly, the conductivity of the dialysate within a bag,changes in the bag's sodium concentration, and therefore conductivity,can be monitored and measured by tracking the corresponding changes tothe magnetic field generated by the coil 1788.

Circuit 1780 enables the accurate measurement of changes in the magneticfield generated by the coil 1788. When the circuit 1780 is driven at itsresonant frequency, energy is transferred back and forth betweeninductive element L 1787 and capacitor 1781. At resonance, energy lossesare proportional to the I²R losses of R_(S) and R_(P). To maintain aconstant AC voltage across C 1781, energy must be supplied to thecircuit 1780 and the supplied energy must equal the energy loss of R_(P)1785 and R_(S) 1786. When the L 1787 and C 1781 elements are placed in aPierce oscillator with automatic gain control, the control voltage willbe proportional to the electrical conductivity of the fluid beingsensed, since the oscillator will require more energy to oscillate withhigher resistive field losses due primarily to changes in dialysateconductivity arising from changes in sodium concentration levels.

As mentioned previously with reference to FIG. 17B, the reservoir pan issuspended in a scale mechanism for accurate measurement of the weightand for maintaining volumetric balance of the dialysate fluid in thecircuit during dialysis. The suspension points 1755 for the scalemechanism are illustrated in FIG. 17C. In one embodiment, foursuspension points 1755 are provided, each of which includes a weighingmechanism, as previously described. In addition to the four suspensionpoints 1755, the reservoir assembly subsystem 1700 also includes a levelsensor. The level sensor allows for computation of accurate weight evenif the reservoir bag is not level. FIG. 17C also illustrates pins 1756on the top of the reservoir assembly module 1700, which can be used toprovide electrical connection to a control and/or pumping unit which, asmentioned earlier, may be mounted on the top of the reservoir assembly.

Referring to FIG. 18A, the flexure 1805 comprises a plurality ofattachment points 1861 where the flexure is secured to the externalreservoir housing. The flexure further comprises magnetic bodies 1862,such as two magnets, and a hall sensor 1864. The base 1867 of theflexure 1805 is attached to the top surface 1715 of scale 1718. As thescale 1718 displaces due to the application of a weight load (e.g. whenthe reservoir bag fills with dialysate the bag presses on surface 1715,thereby pulling scale 1718 downward), the flexure 1805, which isconnected to the scale at one end and the external housing at anotherend, will flex and the magnet 1862, mounted on the one end of theflexure 1805, will track that change by virtue of changes to themagnetic field generated by the magnetic body 1862. The hall sensor 1864detects changes in the magnetic field strength. One of ordinary skill inthe art would understand how to translate this sensed magnetic fieldchange into a measure of the applied weight load.

FIG. 18B is a cross-section illustration of another embodiment of areservoir unit 1821 of the dialysis system. The unit 1821 has a doublepan structure, which defines therein an internal space housing a heatingelement, for improved fluid heating and isolation of the conductiveelements from water. Referring to FIG. 18B, the reservoir unit 1821comprises an internal pan 1815 having a base and four sidewalls fused orotherwise attached thereto. The internal pan 1815 defines a firstrectangular prism volume (or a cuboid, right rectangular prism, orrectangular parallelepiped) 1816 within which recycled water for thedialysis treatment is stored. The reservoir unit 1821 further comprisesan external shell 1810 having a base and four sidewalls fused orotherwise attached thereto. The external shell 1810 defines a secondrectangular prism volume 1817 within which a heating element 1820 andthe internal pan 1815 are housed. The external shell 1810 and internalpan 1815 are fused or connected, either fixedly or removably, to fullyenclose the heating element 1820. The external shell 1810 and/orinternal pan 1815 comprise protrusions, members, or extensions 1818 thatlaterally extend outward from the top of at least one of the externalshell 1810 and/or internal pan 1815.

A heating element 1820, such as a heating pad, covers substantially theentire outer surface of the internal pan 1815. In one embodiment, theheating element comprises an Arlon polyester sheet. Conductive elements,such as wires, extend from the heating pad 1820, through the externalshell 1810, and connect to electrical contact elements on the outersurface of the back side of the external shell 1810. The conductiveelements supply power from the dialysis system through electricalcontacts connected to the frame of the base unit, through electricalcontacts on the external back side surface of the external shell 1810,into conductive elements, and to the heating pad 1820. The heatingelement 1820, when activated, heats the internal pan 1815 and fluidtherein evenly. In one embodiment, the heating element 1820 comprises a300 W to 600 W heating pad, enabling the unit to heat a starting volumebetween 1 and 6 liters in the internal pan 1815 from room temperature to36 to 39° C. within 15 to 45 minutes. The external shell 1810 is sizedsuch that the internal pan 1815 and heating pad 1820 combination willfit snugly within the second rectangular prism volume 1817. Stateddifferently, the internal pan 1815 is sized to be similar in shape to,but smaller than, the external pan 1810, thereby permitting the internalpan 1815 to fit within the external pan and define a substantiallyequidistant space between the outer side wall surfaces of the internalpan 1815 and the internal side wall surfaces of the external pan 1810.Once assembled, the internal pan 1815 is fused to the external shell1810 so that all conductive elements are isolated from fluids.

FIG. 18C is a view of one embodiment of the electrical contact elements1830 on the reservoir unit. A plurality of electrical contact elements1830 are secured within a housing 1834 built into the back side of theexternal shell 1810. The electrical contact elements 1830 are covered bya contact plate 1835, as can be seen in FIG. 18D. The contact elements1830 and covering contact plates 1835 are positioned to permit reliablealignment with corresponding contact elements on the inside of thedialysis machine once the reservoir unit is installed. In addition, thecontact plates 1835 are sufficiently sized to allow transfer of therequired wattage levels to the heating pad to achieve the desired rateof temperature increase of the fluid. In one embodiment, the contactelements comprise a plurality of contact pins. The pins are rated tocarry the requisite amount of amperage to power the heating element. Theheating element requires approximately 15 amps. In one embodiment, thereservoir unit includes nine pins with each pin capable of transferringapproximately 9 amps, for a total of over 80 amps. The contact platescovering the pins preferably come into direct physical and electricalcontact with the electrical contacts within the dialysis machine toallow for the transfer of power.

FIG. 18D also depicts a continuous lip forming protrusions 1840 (ormembers, shelf structures, extensions, or linear structures) extendingoutwardly along all four top edges of the reservoir unit. In oneembodiment, the protrusions 1840 are fused or molded into the top edgesof the internal pan and/or top edges of the external shell. Theprotrusions 1840 along the sides parallel to the external shellsidewalls are sized to fit onto tracks within the base unit of thedialysis machine. The protrusions 1840 can be used to handle thereservoir unit during installation and removal. The protrusions 1840extend beyond the edge of the external shell and thereby provide extraprotection against liquid ingress into the junction between the internalpan and external shell.

FIG. 18E is an oblique front view illustration of one embodiment of theinside of the bottom section of the dialysis system, depicting a firsthorizontal track 1845 for receiving, sliding, and supporting the sideprotrusions 1840 of the reservoir unit. An identical track is positionedon the opposite side of the dialysis machine. The side protrusions 1840act as rails and are slid onto the tracks 1845 until the reservoir unitreaches a specific, predefined depth into the dialysis machine. In oneembodiment, at the predefined depth, the side protrusions 1840 pass asmall raised tab 1850 positioned on the front end of each track 1845.After passing the tab 1850, the protrusions fall slightly and come torest in the tracks 1845. The tabs 1850 help to position the reservoirunit properly in the dialysis machine and provide a snug fit. The snugfit ensures that the electrical contact elements at the back of thereservoir unit remain in contact with the electrical contact elements onthe inside of the dialysis machine during movement. To remove thereservoir unit, the unit is lifted up slightly, thereby pulling the sideprotrusions 1840 up above the tabs 1850, and slid back out of the baseunit of the dialysis machine.

Positioned above each first horizontal track 1845 is a second horizontaltrack 1848. The second horizontal tracks 1848 slidably receive a lowweight plastic ceiling frame from which hangs a plastic bag that linesthe reservoir and contains the liquid. At least one first tube passesthrough the ceiling and into the liquid to draw liquid from thereservoir and into the dialysis system and, at least one second tubepasses through the ceiling and into the liquid to return liquid to thereservoir. The second horizontal tracks 1848 are suspended by a secondinternal frame of the dialysis machine that is separate from a firstinternal frame supporting the first horizontal tracks 1845. As such,items suspended on the second internal tracks 1848 do not factor intoweight measurements calculated for items suspended by the firsthorizontal tracks 1845. The weight of the plastic bag lining thereservoir unit is negligible.

FIG. 18F is an oblique front view illustration of one embodiment of aplastic ceiling frame 1852 positioned above a reservoir unit 1821. Whenin operation, the ceiling frame 1852 rests on the second horizontaltracks and the lining plastic bag 1855 hangs from the ceiling frame 1852and sits in the reservoir unit 1855. The bag 1855 is filled with liquidfor the dialysis procedure. In the pictured embodiment, the ceilingframe 1852 includes a first tube 1853 for drawing liquid from thereservoir 1821 for the dialysis procedure and a second tube 1854 forreturning liquid to the reservoir 1821. The plastic bag 1855 thereforecomprises a first solid plastic sheet, or ceiling frame, 1852 adapted toslide within the second horizontal tracks and provide a solid structurecapable of holding up a flexible and substantially transparent plasticbag that is fixedly attached to the frame 1852.

FIG. 18G is a front view illustration of one embodiment of the inside ofthe base unit 1803 which receives the reservoir unit, depicting contactelements 1833 therewithin. Once the reservoir unit has been slid intoplace, the contact plate with contact elements on the external shellautomatically physically aligns and makes a removable physicalconnection with the contact elements 1833 on the inside of the base unit1803 of the dialysis machine.

The contact elements 1833 deliver the requisite current to the contactplate of the reservoir unit to insure the heating pad temperatureincreases at the required rate. The contact elements 1833 and firsthorizontal tracks 1845 are both integrated into a first internal frame1860, which, in one embodiment, supports a central flexure assembly 1812to allow for measurement of the contents of the reservoir unit. Thefirst frame 1860 suspends the reservoir unit via the integrated tracks1845 and flexure assembly 1812. By supporting both the reservoir unitand the contact elements 1833, the frame 1860 insures that the contactplate 1835 of the reservoir unit and the base unit's contact elements1833 will remain aligned and in reliable, constant contact as the systemis moved and the reservoir unit sways due to the movement of fluid. Inother various embodiments, suspension of the reservoir unit includesdifferent flexure systems to permit the accurate weighing of fluidtherewithin. Also depicted is the second internal frame 1865 with a pairof second horizontal tracks 1848. The second horizontal tracks 1848suspend the ceiling frame from which hangs the plastic bag for thereservoir unit. The second internal frame 1865 and first internal frame1860 are sufficiently distinct structures such that loads placed on thesecond internal frame 1865 do not necessarily translate into loads bornby the first internal frame 1860.

FIGS. 18H and 18I are front and side view illustrations, respectively,of one embodiment of a dialysis machine, depicting a flexure assembly1812 and first 1860 and second 1865 internal frames therein. The flexureassembly and first and second frames are similar to those described inco-pending U.S. patent application Ser. No. 13/726,450, entitled “LoadSuspension and Weighing System for a Dialysis Machine Reservoir”, filedon Dec. 24, 2012 and assigned to the applicant of the present invention,which is hereby incorporated by reference in its entirety. Referring toFIGS. 18H and 18I, the front and sides of the dialysis machine have beenmade transparent and the reservoir unit has been removed to enhancevisualization. The dialysis machine comprises top 1801 and bottom 1803sections. In one embodiment, the bottom section 1803 houses the flexureassembly 1812 and associated components. The second internal frame 1865is attached to a member that is the bottom surface of the top of theframe defining the bottom section 1803 of the dialysis machine. Thesecond internal frame 1865 includes a top plate, two side walls withopenings 1866 for passage of the top plate of the first internal frame1860, and a pair of horizontal tracks 1848. In one embodiment, thehorizontal tracks 1848 of the second internal frame 1865 extend alongthe front to back axis of the dialysis machine, from a point proximatethe front of the machine to a point proximate the back of the machine.

A flexure assembly 1812 is attached to the same member to which thesecond internal frame 1865 is attached (the bottom surface of the top ofthe frame defining the bottom section 1803 of the dialysis machine). Inone embodiment, a top plate of the first internal frame 1860 connects tothe bottom of the flexure assembly 1812. The first internal frameincludes a top plate, two sides with horizontal tracks 1845, and a backplate 1832 with electrical contact elements 1833. In one embodiment, thehorizontal tracks 1845 of the first internal frame 1860 extend along thefront to back axis of the dialysis machine, from a point proximate thefront of the machine to a point proximate the back of the machine.Preferably, the back plate 1832 is rectangular shaped and includes theelectrical contact elements 1833 which align with and contact theelectrical contact plate on the insertion side of the reservoir unit.The first internal frame 1860 includes a pair of tracks 1845, with onetrack extending along each side of the dialysis machine. Each track 1845is connected to the back plate 1832 at its back end. When inserted, thereservoir unit is suspended on the tracks 1845 of the first internalframe 1860. It should be appreciated that the present specificationdiscloses a dialysis system comprising a top member attached to aflexure assembly which, in turn, is attached to a first frame comprisinga pair of linear tracks and a vertical side wall having electricalcontacts. The top member is further physically attached to a secondframe comprising a pair of linear tracks.

FIG. 18J is a top-down front view illustration of one embodiment of thereservoir unit 1821 installed within the bottom section of the dialysissystem. In the pictured embodiment, the reservoir door 1826 is arrangedto fold forward down to open and fold back up to close, rather thanopening to the right or left. The reservoir door 1826 is depicted foldeddown and open.

The front door opens widely (approximately 100 degrees), for loading adisposable manifold. Having a wide opening facilitates manifold loadingand easy cleaning of the faces of the machine and inside of the door.Having the door close and cover the moving parts of the device makes itsafer and more robust, which is particularly important for home use.Additionally, having the front door house the display saves space andre-enforces the important point that the device is not to be operatedunless the disposables are in place and the door is closed. The doorprovides the necessary occlusion force on the manifold and its pumpsegments. The door also contains a touch screen, audio alarm, and manualstop button in the face of the door.

In one embodiment, the door is held in a fully closed position by anelectric stepper motor. This motor is operated via the user interfaceand, in particular, by a user pressing a button when the door is readyto be fully closed or opened. To ensure proper pressure is placed on themanifold structures by the door and pump shoes, it is preferred to havean electronic mechanism by which the door is closed and sufficientclosing door force is generated. In one embodiment, a closing door forceof 90 to 110 lbs is generated.

Referring to FIGS. 19 and 20, one embodiment of the power door closingmechanism 1900 is shown. A stepper motor 1906 is mechanically engagedwith a lead screw 1916, such that, when actuated by a controller, thestepper motor 1906 causes the lead screw 1916 to turn and, consequently,to cause rod 1918, 2018 to apply a motive force to a hook. The hook,located under member 2040, serves to latch onto U-latch 2030 and, whenpulled, turned, or otherwise moved inward toward stepper motor 1906,pull the U-latch 2030 further closed, thereby applying the requisiteclosing door force. The hook is physically engaged with rod 1918, 2018and can be manipulated to pull the U-latch 2030 tightly closed or toloosely engage with the U-latch 2030. The power closing system ismounted and kept in proper orientation by mounting brackets 1905.

Referring to FIG. 21, operationally, a user closes the door sufficientlyto engage the U-latch 2110 on the door with the hook 2150 inside theinternal volume of the controller unit. A user then indicates to theportable dialysis machine a desire to close the door, preferably througha mechanical button or graphical user interface icon, which, whenpressed, sends a signal to a controller that, in turn, actuates thestepper motor. The stepper motor applies a motive force to the hook2150, which then pulls the engaged U-latch 2110 tightly closed. In oneembodiment, a controller monitors the torque force being applied by themotor and, when it reaches a pre-defined limit, deactivates the steppermotor. In another embodiment, a hall device positioned proximate to thelead screw senses the extension of the lead screw and determines theextent of movement of the screw. If the screw has sufficiently moved inthe direction of creating greater closing door force, the hall sensortransmits a signal to the controller to deactivate the motor.Alternatively, the sensor constantly transmits a signal indicative ofthe extension of the screw, which is then interpreted by the controllerto determine if sufficient motive force has been applied, and whetherthe stepper motor should be deactivated. In any of these embodiments, ifthe motor over torques, a pre-set distance is exceeded, or the door doesnot reach its fully closed position in a predetermined time, acontroller can actuate the motor to stop and reverse to a fully openstate. The controller can also cause a visual and/or auditory alarm tosound.

When a user wishes to open the door, a mechanical button or graphicaluser interface icon is activated, sends a signal to a controller that,in turn, actuates the stepper motor in reverse. The hook then becomesloosely engaged with the U-shaped latch. A mechanical release button isthen pressed to disengage the loosely engaged hook from the U-shapedlatch.

In addition to providing the requisite closing force, this power doorclosing mechanism has several important features. First, it is designedto avoid obstructions from being caught in the door and subject to thepowerful door closing force. Referring to FIG. 21, the area recessedinto the door 2105 for accepting a manifold 2130 is surrounded by a foursided edge guard 2107 which prevents a door latch from engaging with alatch receiver on the top unit if a blockage, such as person's finger orimproperly installed disposable, is between the door 2105 and the topunit's base plate. Door 2105 comprises an internal surface 2106 to whicha metallic casing 2125 is attached. In one embodiment, the top surfaceof the internal surface 2106 of the door 2105 is securely attached to anexternal surface of the casing 2125. The casing 2125 is substantiallyrectangular and defines a cavity with four sides 2107 and a base 2108creating an internal volume. The cavity opens toward the manifoldstructure 2130 of the dialysis system 2100 and encompasses and surroundsthe manifold structure 2130 and guard 2140, which is preferably aplastic shroud that surrounds the manifold structure 2130 at its top andsides. Attached to the surface of the base 2108 are the pump shoes 2115and at least one U-shaped latch 2110, which protrudes toward the backplate. Integrated within, and extending out of, the guard is a hook 2150which is configured to securely engage and disengage the U-shaped latch2110. If the door is correctly closed and nothing is caught between thedoor and the guard, then the U-shaped latch will be mechanically hookedby the power-door lock hook mechanism. If an obstruction is in the doorpathway, the metal casing 2125 will be unable to extend into theinternal volume of the top unit (and encompass the guard) and,therefore, the U-shaped latch will be unable to engage the hook, therebypreventing the mechanical hooking and accidental power closing of thedoor when an obstruction is in place.

Second, the mechanical button release can only be actuated when thepower closing door force has been dissipated through the reverse motionof the stepper motor, thereby preventing an accidental release of, andrapid opening of, the door. Referring to FIGS. 19 and 20, when the dooris closed and locked, a collar 2050 on the button shaft 1907, 2007 turns90 degrees moving a push pin away from the power-door locking hook. Thecollar 2050 is turned by virtue of rod 1921, which is connected to thecollar at point 2045 and in mechanical engagement with lead screw 1916.The collar 2050 is spring loaded and locked by a small pin solenoid. Ifthe user presses the button when in the locked position the button willmove into the machine but, because of the displacement caused by theturning of the collar, will not disengage the hook, thereby preventingthe door from opening.

If the power is lost or unintentionally terminated, then the pinsolenoid will release, allowing the collar to turn back 90 degrees andplacing the push-pin in proper alignment. Then when the user presses thebutton the push pin will contact the power-door hook and release thedoor latch. This mechanism provides the convenience and safety back upof a mechanical door release without concern that the mechanical doorrelease can accidentally be activated to cause the door to swing openwith tremendous force. It should be appreciated that the term “hook” or“latch” should be broadly defined as any protrusion or member capable ofphysically or mechanically engaging with another protrusion or member.It should further be appreciated that the term “U-shaped latch” is notlimiting and any latching or hooking mechanism, as defined above, can beused.

As discussed above, shelving space formed by the bottom unit andsurrounding the top unit employs drainage paths with fluid sensors, inmultiple locations internal and external to the device, in order toenable zoned leak detection. Specifically, by building in drainagepaths, with optical leak sensors, into the external body of the device,the system captures and routes fluids potentially leaked from theexternal components (like the sorbent canister) to the optical leaksensors. For example, in one embodiment, the surface 2132 of the topunit upon which the manifold 2130 is mounted and against which thecasing 2125 rests and forms a cavity, comprises angled surfaces 2190that form angled edges which serve to capture moisture emitted or leakedfrom the manifold 2130, and areas around the manifold 2130, and directthe moisture, through force of gravity, to a centrally positionedmoisture sensor 2180. Preferably, the angled surfaces 2190 aresufficiently inclined to cause moisture landing on the angled edges tomove downward toward one or more moisture sensors 2180 positioned toreceive the moisture. In one embodiment, one moisture sensor 2180 iscentrally located, relative to the position of the manifold 2130, andequidistant from the ends of each angled surface 2190.

In one embodiment, integrated within the external housings of the bottomunit are at least three different optical leak detectors. Referring toFIG. 22, the top surface of bottom unit 2202 is slightly angled, withcenter 2280 raised relative to sides 2281 and 2282. In one embodiment,the surface tilts downward, from center area 2280 to sides 2281 and2282, by an angle of 1 to 10 degrees, preferably 3 degrees. Channels2287 encircle the top surface of the bottom unit, extend around theperiphery, extend through the center of the top surface, and/or extendthrough any other portion of the top surface. By virtue of the angledtop surface of the bottom unit 2202, the channels 2287 are also angledfrom the center 2280 to the sides 2281, 2282. In another embodiment, thetop surface is also slightly angled downward from back side 2291 tofront surface 2290. The angled channels 2287 cause fluids to be directedaway from the center and/or back of the system forward and to the sideswhere leak detectors 2288 are positioned and are in fluid communicationwith the channels 2287.

A first optical leak detector 2288 is located on the front right cornerof the top surface of the bottom unit 2202. A second optical leakdetector 2288 is located on the front left corner of the top surface ofthe bottom unit 2202. Each leak detector is positioned within a well orcavity and comprises an optical sensor, which is located in the side ofthe well. The optical sensor detects fluids that have drained and/orbeen channeled to the wells and transmits a detected signal to acontroller in the top unit. The detected signal is processed by aprocessor to determine if a leak has occurred. Detected signals are thenstored and, if required, the processor causes an alarm or alert todisplay on the GUI. The well or cavity preferably comprises a roundedbase to permit the user to easily wipe the well dry. FIG. 23 shows amore detailed view of the top surface of the bottom unit 2302 withchannels 2387 and leak detector 2388 positioned within well 2397.

Referring to FIG. 24, at least one additional leak detector is locatedwithin the bottom unit 2402 and, more particularly inside the reservoir2403, within which a scale 2404 is integrated. Channels 2405 areintegrated into the reservoir structure, such as the internal housing ormetal bag holder, and are preferably angled from one side to the otherside or from the center to either side. In one embodiment, the angle isin the range of 1 to 10 degrees and more particularly 3 degrees. A well2410 housing a leak detector is integrated into the reservoir housingand in fluid communication with the channels 2405 in one or both sidesof the reservoir housing. If a leak occurs in the disposable bag, fluidwill drain to the corner of the metal pan or reservoir housing viachannels 2405 and be directed into at least one well with a leak sensor2410.

The drainage paths serve two functions: a) to make sure fluid does notenter the instrument and b) to make sure that a leak is quicklycontained and routed to a sensor which can trigger an alert or alarm.Additionally, the device preferably also includes fluid drainagechannels leading to wells with optical sensors on the interior of thedevice. So, for instance, if there is a leak in the internal reservoir,the fluid is routed away from critical components and an optical sensorwarns of the leak. Based on the sensor activated, the GUI can present analarm to the user and can specifically identify the location of thefluid leak. By providing several independent zones of leak detection(several fluid sensors and drainage paths), the instrument can guide theuser to find the leak quickly. Having multiple channels and sensorsallows the system to partially, automatically, identify the source ofthe leak and offer graphic assistance, toward remedy of the problem, tothe user.

Referring now to FIG. 25, when a sorbent cartridge 2580 fills with wastematerial, it expands and, if not properly anchored to the base, can tipover. In one embodiment, the sorbent cartridge 2580 is anchored to thebase 2520, and temporarily physically attached thereto, by a pluralityof connectors 2540. The base 2520 is a planar structure havingconnectors 2510 that are configured to removably attach to matingconnectors on the base of the dialysis system. In one embodiment, thebase unit 2520 comprises two mating connectors 2510 having complementarymating connectors on the base unit. The connectors 2540 comprise atleast two, preferably three, or optionally more than three L-shapedmembers. In a three connector configuration 2540, the connectors areequally distributed around a circumference that is slightly larger thanthe periphery of the base of the sorbent cartridge 2580. When thesorbent cartridge 2580 is placed within the connectors, it fits snuglytherein and is kept in place by the weight of the cartridge 2580. Theplanar surface 2520 further comprises a second set of connectors 2550that comprise at least two, preferably three, or optionally more thanthree L-shaped members. In a three connector configuration 2550, theconnectors are equally distributed around a circumference that isslightly larger than the periphery of the base of a concentrate jar.When the concentrate jar is placed within the connectors 2550, it fitssnugly therein and is kept in place by the weight of the jar 2550.

Exemplary Blood and Dialysate Fluid Paths

The disclosed embodiments can be used to provide dialysis treatments toa patient.

FIG. 26 is a functional block diagram of one embodiment of amultiple-pass sorbent-based dialysis system of the present invention. Inone embodiment, dialysis system 2600 employs a dialyzer cartridge 2602comprising a high flux membrane to remove toxins from the blood both bydiffusion and by convection. The removal of toxins by diffusion isaccomplished by establishing a concentration gradient across thesemi-permeable membrane by allowing a dialysate solution to flow on oneside of the membrane in one direction while simultaneously allowingblood to flow on the other side of the membrane in the oppositedirection. To enhance removal of toxins using hemodiafiltration, asubstitution fluid is continuously added to the blood either prior tothe dialyzer cartridge (pre-dilution) or after the dialyzer cartridge(post-dilution). An amount of fluid equal to that of the addedsubstitution fluid is “ultra-filtered” across the dialyzer cartridgemembrane, carrying the added solutes with it.

Referring to both FIGS. 26 and 27 simultaneously, in one embodiment, theblood containing toxins is pumped from a blood vessel of a patient by ablood pump 2601, 2701 and is transferred to flow through dialyzercartridge 2602, 2702. Optionally, inlet and outlet pressure sensors2603, 2604, 2703, 2704 in the blood circuit measure the pressure ofblood both before it enters the dialyzer cartridge 2602, 2702 via theblood inlet tube 2605, 2705 and after leaving the dialyzer cartridge2602, 2702 via the blood outlet tube 2606, 2706. Pressure readings fromsensors 2603, 2604, 2628, 2703, 2704, 2728 are used as a monitoring andcontrol parameter of the blood flow. A flow meter 2621, 2721 may beinterposed in, or otherwise in pressure communication with, the portionof blood inlet tube 2605, 2705 that is located directly upstream fromthe blood pump 2601, 2701. The flow meter 2621, 2721 is positioned tomonitor and maintain a predetermined rate of flow of blood in the impureblood supply line. A substitution fluid 2690 may be continuously addedto the blood either prior to the dialyzer cartridge (pre-dilution) orafter the dialyzer cartridge (post-dilution).

In one embodiment, referring to both FIGS. 26 and 27, dialyzer cartridge2602, 2702 comprises a semi-permeable membrane 2608, 2708 that dividesthe dialyzer 2602, 2702 into a blood chamber 2609, 2709 and a dialysatechamber 2611, 2711. As blood passes through the blood chamber 2609,2709, uremic toxins are filtered across the semi-permeable membrane2608, 2708 due to convective forces. Additional blood toxins aretransferred across the semi-permeable membrane 2608, 2708 by diffusion,primarily induced by a difference in concentration of the fluids flowingthrough the blood and dialysate chambers 2609, 2709 and 2611, 2711respectively. The dialyzer cartridge used may be of any type suitablefor hemodialysis, hemodiafiltration, hemofiltration, orhemoconcentration, as are known in the art. In one embodiment, thedialyzer 2602, 2702 contains a high flux membrane. Examples of suitabledialyzer cartridges include, but are not limited to, Fresenius® F60, F80available from Fresenius Medical Care of Lexington, Mass., Baxter CT110, CT 190, Syntra® 160 available from Baxter of Deerfield, Ill., orMinntech Hemocor HPH® 1000, Primus® 1350, 2000 available from Minntechof Minneapolis, Minn.

In one embodiment of the present invention, dialysate pump 2607, 2707draws spent dialysate from the dialyzer cartridge 2602, 2702 and forcesthe dialysate into a dialysate regeneration system 2610, 2710 and back2613, 2713 into the dialyzer cartridge 2602, 2702 in a multiple passloop, thus generating “re-generated” or fresh dialysate. Optionally, aflow meter 2622, 2722 is interposed in the spent dialysate supply tube2612, 2712 upstream from dialysate pump 2607, 2707 which monitors andmaintains a predetermined rate of flow of dialysate. A blood leak sensor2623, 2723 is also interposed in spent dialysate supply tube 2612, 2712.

The multi-pass dialysate regeneration system 2610, 2710 of the presentinvention comprises a plurality of cartridges and/or filters containingsorbents for regenerating the spent dialysate. By regenerating thedialysate with sorbent cartridges, the dialysis system 2600, 2700 of thepresent invention requires only a small fraction of the amount ofdialysate of a conventional single-pass hemodialysis device.

In one embodiment, each sorbent cartridge in the dialysate regenerationsystem 2610, 2710 is a miniaturized cartridge containing a distinctsorbent. For example, the dialysate regeneration system 2610, 2710 mayemploy five sorbent cartridges, wherein each cartridge separatelycontains activated charcoal, urease, zirconium phosphate, hydrouszirconium oxide and activated carbon. In another embodiment eachcartridge may comprise a plurality of layers of sorbents described aboveand there may be a plurality of such separate layered cartridgesconnected to each other in series or parallel in the dialysateregeneration system. Persons of ordinary skill in the art wouldappreciate that activated charcoal, urease, zirconium phosphate, hydrouszirconium oxide and activated carbon are not the only chemicals thatcould be used as sorbents in the present invention. In fact, any numberof additional or alternative sorbents, including polymer-based sorbents,could be employed without departing from the scope of the presentinvention.

The sorbent-based multiple-pass dialysis system of the present inventionprovides a plurality of advantages over conventional single-passsystems. These include:

-   -   No requirement of a continuous water source, a separate water        purification machine or a floor drain as the system of present        invention continuously regenerates a certain volume of        dialysate. This allows for enhanced portability.    -   The present system requires a low amperage electrical source,        such as 15 amps, because the system recycles the same small        volume of dialysate throughout the diafiltration procedure.        Therefore, extra dialysate pumps, concentrate pumps and large        heaters used for large volumes of dialysate in single pass        dialysis systems are not required.    -   The present system can use low volumes of tap water, in the        range of 6 liters, from which dialysate can be prepared for an        entire treatment.    -   The sorbent system uses sorbent cartridges that act both as a        water purifier and as a means to regenerate used dialysate into        fresh dialysate.

While the current embodiment has separate pumps 2601, 2701, 2607, 2707for pumping blood and dialysate through the dialyzer, in an alternateembodiment, a single dual-channel pulsatile pump that propels both bloodand dialysate through the hemodiafiltration system 2600, 2700 may beemployed. Additionally, centrifugal, gear, or bladder pumps may be used.

In one embodiment, excess fluid waste is removed from the spentdialysate in the spent dialysate tube 2612, 2712 using a volumetricwaste micro-pump 2614, 2714 and is deposited into a waste collectionreservoir 2615, 2715 which can be periodically emptied via an outletsuch as a tap. An electronic control unit 2616 comprising amicroprocessor monitors and controls the functionality of all componentsof the system 2600.

In one embodiment, diafiltered blood exiting dialyzer cartridge 2602,2702 is mixed with regulated volumes of sterile substitution fluid thatis pumped into the blood outlet tube 2606, 2706 from a substitutionfluid container 2617, 2717 via a volumetric micro-pump 2618, 2718.Substitution fluid is typically available as a sterile/non-pyrogenicfluid contained in flexible bags. This fluid may also be producedon-line by filtration of a non-sterile dialysate through a suitablefilter cartridge rendering it sterile and non-pyrogenic.

FIG. 28 is a functional block diagram showing one embodiment of anultrafiltration treatment system 2800 of the present invention. As shownin FIG. 28, blood from a patient is drawn into blood inlet tubing 2801by a pump, such as a peristaltic blood pump, 2802 that forces the bloodinto a hemofilter cartridge 2804 via blood inlet port 2803. Inlet andoutlet pressure transducers 2805, 2806 are connected in-line just beforeand after the blood pump 2802. The hemofilter 2804 comprises asemi-permeable membrane that allows excess fluid to be ultrafiltratedfrom the blood passing therethrough, by convection. Ultrafiltered bloodis further pumped out of the hemofilter 2804 through blood outlet port2807 into blood outlet tubing 2808 for infusion back to into thepatient. Regulators, such as clamps, 2809, 2810 are used in tubing 2801and 2808 to regulate fluid flow therethrough.

A pressure transducer 2811 is connected near the blood outlet port 2807followed by an air bubble detector 2812 downstream from the pressuretransducer 2811. An ultrafiltrate pump, such as a peristaltic pump, 2813draws the ultrafiltrate waste from the hemofilter 2804 via UF(ultrafiltrate) outlet port 2814 and into the UF outlet tubing 2815. Apressure transducer 2816 and a blood leak detector 2817 are transposedinto the UF outlet tubing 2815. Ultrafiltrate waste is finally pumpedinto a waste collection reservoir 2818 such as a flask or soft bag,attached to the leg of an ambulatory patient and equipped with a drainport to allow intermittent emptying. The amount of ultrafiltrate wastegenerated can be monitored using any measurement technique, including ascale 2819 or flow meter. The microcontroller 2820 monitors and managesthe functioning of the blood and UF pumps, pressure sensors as well asair and blood leak detectors. Standard luer connections such as luerslips and luer locks are used for connecting tubing to the pumps, thehemofilter and to the patient.

Another blood and dialysate circuit capable of being implemented or usedin the embodiments of the dialysis systems is shown in FIG. 29. FIG. 29depicts the fluidic circuit for an extracorporeal blood processingsystem 2900 used for conducting hemodialysis and hemofiltration. In oneembodiment of the present invention, the system 2900 is implemented as aportable dialysis system which may be used by a patient for conductingdialysis at home. The hemodialysis system comprises two circuits—a BloodCircuit 2901 and a Dialysate Circuit 2902. Blood treatment duringdialysis involves extracorporeal circulation through an exchanger havinga semi permeable membrane—the hemodialyzer or dialyzer 2903. Thepatient's blood is circulated in the blood circuit 2901 on one side ofthe membrane (dialyzer) 2903 and the dialysate, comprising the mainelectrolytes of the blood in concentrations prescribed by a physician,is circulated on the other side in the dialysate circuit 2902. Thecirculation of dialysate fluid thus provides for the regulation andadjustment of the electrolytic concentration in blood.

The line 2904 from the patient, which transports impure blood to thedialyzer 2903 in the blood circuit 2901 is provided with an occlusiondetector 2905 which is generally linked to a visual or audible alarm tosignal any obstruction to the blood flow. In order to preventcoagulation of blood, delivery means 2906, such as a pump, syringe, orany other injection device, for injecting an anticoagulant—such asheparin, into blood is also provided. A peristaltic pump 2907 is alsoprovided to ensure flow of blood in the normal (desired) direction.

A pressure sensor 2908 is provided at the inlet where impure bloodenters the dialyzer 2903. Other pressure sensors 2909, 2910, 2911 and2912 are provided at various positions in the hemodialysis system totrack and maintain fluid pressure at desired levels at specific pointswithin the respective circuits.

At the point where used dialysate fluid from the dialyzer 2903 entersthe dialysate circuit 2902, a blood leak sensor 2913 is provided tosense and warn of any leakage of blood cells into the dialysate circuit.A pair of bypass valves 2914 is also provided at the beginning and endpoints of the dialysate circuit, so that under conditions of start up,or at other times as deemed necessary by the operator, the dialyzer canbe bypassed from the dialysate fluid flow, yet the dialysate fluid flowcan still be maintained, i.e. for flushing or priming operations.Another valve 2915 is provided just before a priming/drain port 2916.The port 2916 is used for initially filling the circuit with a dialysatesolution, and to remove used dialysate fluid after, and in someinstances during, dialysis. During dialysis, valve 2915 may be used toreplace portions of used dialysate with high concentrations of, forinstance, sodium with replenishment fluid of appropriate concentrationso that overall component concentration of the dialysate is maintainedat a desired level.

The dialysate circuit is provided with two peristaltic pumps 2917 and2918. Pump 2917 is used for pumping dialysate fluid to the drain orwaste container, as well as for pumping regenerated dialysate into thedialyzer 2903. Pump 2918 is used for pumping out spent dialysate fromthe dialyzer 2903, maintaining fluid pressure through the sorbent 2919,and pumping in dialysis fluid from port 2916 to fill the system ormaintain component concentration in the dialysate.

A sorbent cartridge 2919 is provided in the dialysate circuit 2902. Thesorbent cartridge 2919 contains several layers of materials, each havinga role in removing impurities, such as urea and creatinine. Thecombination of these layered materials allows water suitable fordrinking to be charged into the system for use as dialysate fluid. Italso allows closed loop dialysis. That is, the sorbent cartridge 2919enables regeneration of fresh dialysate from the spent dialysate comingfrom the dialyzer 2903. For the fresh dialysate fluid, a lined containeror reservoir 2920 of a suitable capacity such as 0.5, 1, 5, 8 or 10liters is provided.

Depending upon patient requirements and based on a physician'sprescription, desired quantities of an infusate solution 2921 can beadded to the dialysis fluid. Infusate 2921 is a solution containingminerals and/or glucose that help replenish minerals like potassium andcalcium in the dialysate fluid at levels after undesired removal by thesorbent. A peristaltic pump 2922 is provided to pump the desired amountof infusate solution 2921 to the container 2920. Alternatively, theinfusate solution 2921 can be pumped into the outflow line fromreservoir 2920. A camera 2923 may optionally be provided to monitor thechanging liquid level of the infusate solution as a safety check warningof infusate flow failure and/or function as a bar code sensor to scanbar codes associated with additives to be used in a dialysis procedure.Optionally, an ammonia sensor 2928 may be provided.

A heater 2924 is provided to maintain the temperature of dialysate fluidin the container 2920 at the required level. The temperature of thedialysate fluid can be sensed by the temperature sensor 2925 locatedjust prior to the fluid's entry into the dialyzer 2903. The container2920 is also equipped with a scale 2926 for keeping track of the weight,and therefore volume, of the fluid in the container 2920, and aconductivity sensor 2927, which determines and monitors the conductivityof the dialysate fluid. The conductivity sensor 2927 provides anindication of the level of sodium in the dialysate.

A medical port 2929 is provided before blood from the patient enters thesystem for dialysis. Another medical port 2930 is provided before cleanblood from the dialyzer 2903 is returned to the patient. An air (orbubble) sensor 2931 and a pinch clamp 2932 are employed in the circuitto detect and prevent any air, gas or gas bubbles from being returned tothe patient.

Priming set(s) 2933 is/are attached to the dialysis system 2900 thathelp prepare the system by filling the blood circuit 2901 with sterilesaline before it is used for dialysis. Priming set(s) may consist ofshort segments of tubing with IV bag spikes or IV needles or acombination of both pre-attached.

It should be appreciated that, while certain of the aforementionedembodiments disclose the incorporation and use of a port that receivesan injection or administration of an anticoagulant, thereby creating anair-blood interface, such a port can be eliminated if the device canoperate with minimal risk of blood clotting at ports of entry and exit.As further discussed below, the manifold design, particularly withrespect to the internal design of the manifold ports, minimizes the riskof blood clotting, thereby creating the option of eliminating air-bloodinterfaces for receiving an injection or administration of ananticoagulant.

One of ordinary skill in the art would infer from the above discussionthat the exemplary fluidic circuits for a hemodialysis and/orhemofiltration system are complex. If implemented in a conventionalmanner, the system would manifest as a mesh of tubing and would be toocomplicated for a home dialysis user to configure and use. Therefore, inorder to make the system simple and easy to use at home by a patient,embodiments of the present invention implement the fluidic circuits inthe form of a compact manifold in which most components of the fluidiccircuit are integrated into a single piece of molded plastic or multiplepieces of molded plastic that are configured to connect together to forma single operative manifold structure.

Exemplary Manifolds

It should be appreciated that the multi-pass dialysis treatmentprocesses, represented by the blood and dialysate circuits describedabove, can be implemented within, and by, a plurality of blood anddialysate circuits molded into a disposable manifold. As shown in FIG.21, the embodiments of the dialysis system disclosed herein operateusing a manifold 2130 that defines a plurality of blood and dialysatecircuits and places the fluid into pressure, thermal, and/or opticalcommunication with various sensors, meters, and pumps.

In one embodiment, the manifold of the present invention comprises acomposite plastic manifold, into which the blood and dialysate flowpaths are molded. Blood purification system components, such as sensorsand pumps, are placed into pressure, thermal, and/or opticalcommunication within the fluid flow contained within the moldedmanifold. FIG. 30 illustrates the structural elements of a compactmanifold, according to one embodiment of the present invention. Thedisposable manifold pumps and directs fluid flow while measuringpressure in key areas. Those fluids include blood, dialysate, infusateand anticoagulant. In addition, the manifold provides features fordetecting blood leakage from the dialyzer, detecting occlusion in thearterial line, and detecting air in the venous line.

Referring to FIG. 30, in one embodiment, the compact manifold 3000comprises a plurality of plastic layers with components fixedly attachedtherein. More specifically, the manifold 3000 comprises the followingelements:

-   -   Back Cover 3001    -   Pressure Transducer Membranes 3002    -   Valve Membranes 3003    -   Mid Body 3004    -   Front Cover 3005    -   Pump tube segments (not shown in FIG. 30)

The mid-body layer 3004 contains molded in channels on one side. Thesechannels are completed by the front cover layer which is fixedlyattached to the mid-body by any number of methods, including ultrasonicwelding. This combined front cover-mid-body structure forms the majorpart of the fluid pathways within the manifold. On the opposite side ofthe mid-body 3004 there are features that form surfaces for valving andpressure sensing, which communicate to the fluid pathways on the frontcover side of the manifold. The manifold includes elastomeric componentsfor valving and pressure sensing. These elastomeric components arecaptured between the back cover layer and mid-body layer through the useof ultrasonic welding and complete the fluid pathways throughout themanifold.

Referring to FIG. 30, in one embodiment, the manifold 3000 comprisesfive pressure transducer membranes 3002 and three to four membranes 3003for two-way valves. In one embodiment, the two covers 3001 and 3005, andmid body 3004 of the manifold 3000 are molded of a polycarbonatematerial or ABS (acrylonitrile butadiene styrene). The pressuretransducer membranes 3002 and valve membranes 3003 are molded of acommon material, such as Santoprene, or more preferably Sarlink, whichis a medical grade elastomeric polymer. In one embodiment, front andback covers 3005 and 3001 may be molded of optically clear material, atleast transparent to certain preselected wavelengths of light, to allowfor spectroscopic analysis of the fluid(s) contained within.

Additionally, the manifold preferably includes four pumping components.These pumping components are segments of extruded PVC tubing formulatedand dimensioned to have properties optimized for pump use, particularlyroller pump use. This tubing is bonded to barbed fittings that areintegrally molded to the manifold mid-body. One of the four pumpingcomponents is for drawing blood from the patient's artery and pumping itthrough a dialyzer and back to the patient's vein. Two pumpingcomponents are for dialysate flow and one is for infusate delivery tothe dialysate fluid circuit. A separate syringe pump can be used forpumping anticoagulant into the arterial blood pathway, pre-dialyzer.

In one embodiment, the manifold further incorporates tubing ports,preferably in the range of 10-14 and more preferably 12 ports, forconnecting all the fluid pathways within the manifold to othercomponents in the disposable set including dialyzer, sorbent cartridge,bag reservoir, infusate container, patient blood lines, anticoagulant,sensors, priming line and drain, as further discussed below.

In one embodiment, the manifold is shaped like a capital “I”, with afirst segment and a second segment parallel to each other and aconnecting segment that a) is perpendicular to the first segment andsecond segment and b) serves to connect the first and second segments.In one embodiment, the connecting segment connects the middle of thefirst segment to the middle of the second segment, thereby making thedistance between the connecting segment and each end of the first andsecond segments equidistant. It should be appreciated that theconnecting segment can be placed at the ends of the first and secondsegment, thereby making a capital “C” or backwards “C”. The manifold canalso be rotated relative to the dialysis system and need not bepositioned as a capital “I”, e.g. it can be positioned on its side or atan angle. As shown in FIG. 32, in an exemplary embodiment, the manifold3200 has dimensions as follows: L1 and L2 are in the range of 4 to 7inches, and preferably approximately 5.7 inches, L3 and L4 are in therange of 0.5 to 1.5 inches, and preferably approximately 1 inch, L5 isin the range of 2.5 to 4.5 inches, and preferably approximately 3.5inches, and L6 is in the range of 1 to 3 inches, and preferablyapproximately 1.8 inches. While dimensions have been provided, it shouldbe appreciated that the inventions disclosed herein are not limited toany specific dimension, or set of dimensions.

In one embodiment, the assembly process of the manifold 3000 comprisesmating the back cover 3001 to the mid-body 3004 while affixing themembranes 3002 and 3003 into place by having a first side of themembranes physically attach or touch the mid-body and having a secondside of the membranes pass through holes, spaces, or voids 3011 in theback cover 3001. Cover 3001 may be divided into two portions, a topportion and a bottom portion, wherein the top portion comprises a topportion of the central vertical portion 3082 and top horizontal section3080 and the bottom portion comprises a bottom portion of the centralvertical portion 3084 and bottom horizontal section 3085. In thisembodiment, the top and bottom portions of the cover 3001 can beseparately attached to the mid-body 3004 and, relative to a contiguouscover 3001, may not include material in the mid section area 3083 of thecentral vertical portion to save material costs. Preferably, the secondside of the membranes has a tiered structure which permits a first tierto pass through the void 3011 while the second tier remains between theback cover 3001 and mid-body 3004. This affixes the membranes 3002, 3003into the back cover 3001. Furthermore, it is preferred for the mid-body3004 to contain recesses into which the first side of the membranes3002, 3003 rest, thereby affixing them to the mid-body 3004. In analternate configuration, the membranes 3002 and 3003 may be co-molded tothe back cover 3001 in a multi-shot molding process.

One of ordinary skill in the art would appreciate that the variouscomponents of the manifold can be bound or affixed together using anysuitable means. In one embodiment, the seal between the mid-body andback cover is achieved via ultrasonic welding or adhesive. Alternatelylaser welding may be employed. The front cover is bonded to the otherside of the mid body in a similar manner. Pump tubing segments aresolvent bonded into place in one embodiment, or in an alternateembodiment, the segments may be laser welded using a laser absorbingadditive in the plastic.

In one embodiment, the front cover is molded from BASF Terlux 2802HD,ABS, which is clear and will provide visibility to the fluid pathway.The clarity of the ABS will also provide a means for inspecting theintegrity of the ultrasonically welded surfaces. ABS is preferred forits biocompatibility as well as compatibility to ultrasonic welding.Additionally, the front cover can include a molded in textured surfaceto help facilitate a better bond between the front cover and themid-body. This textured surface is a chemical etching process that isknown to persons of ordinary skill in the art. One preferred texturedepth is 0.0045″. Other suitable textures can be laser etched as well.The surface to be welded on the front cover is designed with a 0.003″recess which translates to a 0.003″ raised surface on the mold. Thisprovides an accurate surface to receive the texturing. Once thetexturing takes place on the mold, the height of this 0.003″ surface islowered. Because of the peaks and valleys of the 0.0045″ texture depthit is assumed that the average would be half that amount or 0.00225″.The result would leave the mold in a steel safe condition of 0.00075″.Cover 3005 may also be in the form of just the central vertical portion3090 and not include top and bottom horizontal portions 3091, 3092.Central vertical portion 3090 can be attached to the mid-body 3004 byplacing it in a recessed area, defined by raised edges on the surface ofthe mid-body 3004 opposing the surfacing facing cover 3001, and bondingthe portion 3090 within the recessed region.

In one embodiment, the front cover provides blood flow directors in boththe arterial and venous pathways. These features are designed tominimize hemolysis. The blood flow directors provide for a consistentcross-sectional area throughout the pathway and minimize sharp edges towhich the blood would come in contact without their presence. The wallon the opposite side of the blood flow directors has been relieved toprovide a more consistent wall thickness in the molded plastic part.This will prevent sinks in this area, which could affect the surroundingwelded surfaces. In one embodiment, the front cover wall thickness is0.075″.

Optionally, the front cover has alignment holes provided for assemblypurposes to ensure that the front cover and mid-body are accuratelyaligned during the ultrasonic welding process. The raised bosses aroundthe alignment holes help maximize contact with the alignment pins of thewelding fixture so that the plastic does not melt as easily due tofriction. These bosses do not touch and are not welded to the mid-bodyto ensure that the hole is patent.

FIG. 31 provides a perspective view of the mid-body component of thecompact manifold of the present invention. As is shown in FIG. 31, thecomplete blood and dialysate flow paths 3101 of thehemodialysis/hemofiltration system are molded into the mid-body.Accommodations for the various functional elements of the bloodpurification system, such as pumps, valves and sensors are alsointegrated into the mid-body section of the compact manifold.

The mid-body can be molded from BASF Terlux 2802HD, ABS. Anotheralternative ABS is Lustran 348, White. ABS was chosen for itsbiocompatibility as well as compatibility to ultrasonic welding. Themid-body along with the front cover provides the fluid path channels forthe manifold. The mid-body contains the energy directors for the buttjoint style ultrasonic welding. In one embodiment, the energy director'sdimensions are 0.019″ tall with a 0.024″ wide base. This results in across-sectional area of 0.00023 square inches. The width of the weldingsurface is 0.075″ resulting in a weld volume of about 0.003″×0.075″. Abutt joint style energy director is preferred over other styles, likeshear joints, tongue and groove, step joint, due to its simplicity andability to control the molded part geometry. Vents are provided in theweld geometry to prevent trapped gases from being forced through thewelds resulting in a poor weld that may leak.

The back cover side of the mid-body preferably provides a molded intextured surface to help facilitate a better bond between the back coverand the mid-body. This textured surface is a chemical etching processthat is known to persons of ordinary skill in the art. The preferredtexture depth is 0.0045″. Other suitable textures can be laser etched aswell. The surface to be welded on the mid-body is designed with a 0.003″recess which translates to a 0.003″ raised surface on the mold. Once thetexturing takes place on the mold, the height of this 0.003″ surface islowered. Because of the peaks and valleys of the 0.0045″ texture depthit is assumed that the average would be half that amount or 0.00225″.The result would leave the mold in a steel safe condition of 0.00075″.

The size of the components being welded can have a major impact on thesuccessfulness of the ultrasonic welding process. The larger the surfacearea, the more difficult the welding process becomes. It is importantthat the welding surfaces are accurately controlled. Consistentthickness in the front and back covers is more important than flatnessbecause a cover that is off slightly on flatness will be pressed flatduring the welding process. Flatness on the mid-body is important due tothe structural design that would prevent it from being flattened duringthe welding process. Due to these issues it is very important that theparts are designed correctly and not prone to anomalies like warpage,sinks, dimensional variations, etc. In addition, the mold constructionand quality needs to match high standards that the parts will need tomeet. It would follow that the molding process controls would requirethe highest of standards as well.

The back cover can be molded from BASF Terlux 2802HD, ABS. The backcover contains the energy directors for the butt joint style ultrasonicwelding. The energy director's dimensions are 0.019″ tall with a 0.024″wide base. This results in a cross-sectional area of 0.00023 squareinches. The width of the welding surface is 0.075″ resulting in a weldvolume of about 0.003″×0.075″. This 0.003″ weld volume should beconsidered when determining the geometry of the assembled components.Vents are provided in the weld geometry to prevent trapped gases frombeing forced through the welds resulting in a poor weld that may leak.The alignment holes in the back cover are provided for assembly purposesto ensure that the back cover is accurately aligned to the mid-bodyduring the ultrasonic welding process. The alignment holes in the backcover also provide accurate alignment of the manifold and instrumentwhen properly loaded. The raised bosses around the alignment holes aredesigned to maximize contact with the alignment pins of the weldingfixture so that the plastic does not melt as easily due to friction.These bosses do not touch and are not welded to ensure that the hole ispatent.

Ultrasonic welding was chosen as the method for bonding the manifoldsthree major components because of the low cost of this manufacturingprocess. The relatively low equipment costs and cycle times to createthe weld attribute to this lower manufacturing cost. Once the parts areloaded into the fixture, the welding cycle with horn travel and removal,can be accomplished in seconds. The actual weld time is about onesecond. Other bonding methods include hot plate, laser, and UV adhesive.

Referring to FIG. 31, in one embodiment, the mid-body section 3100 hasintegrated within it three 2-way valves 3107, five pressure transducers3106, an occlusion detector, an air bubble detector and a blood leakdetector. One of ordinary skill in the art would appreciate that thenumber and type of functional components that are integrated within themid-body section 3100 may be varied according to the requirement andapplication of the blood purification system and, therefore, can include1, 2, 3, 4, 6, 7, 8, 9, 10 or more pressure transducers, 1, 2, 4, 5, 6,or more 2-way valves, 0, 2, 3, 4, or more occlusion detectors, 0, 2, 3,4, or more air bubble detectors, 0, 2, 3, 4 or more blood leakdetectors. Additionally, the mid-body section 3100 comprises a pluralityof ports 3103, 3104.

The ports include internal ports 3104 through which fluid flows via pumpsegments (not shown) from and between the first and second segments ofthe manifold 3100. In one embodiment, the first segment has fourinternal ports 3104, two on each side of the point where the firstsegment and connecting segment connect. It should be appreciated thatthe first segment can have 1, 2, 3, 5, 6, 7, or more internal ports. Inone embodiment, the second segment has four internal ports 3104, two oneach side of the point where the first segment and connecting segmentconnect. It should be appreciated that the second segment can have 1, 2,3, 5, 6, 7, or more internal ports. Additionally, it is preferred thatthe position and location of the internal ports of the first segmentmirrors the position and location of the internal ports of the secondsegment. The ports also include external ports 3103 to elements externalto the manifold 3100. In one embodiment, the first segment has twoexternal ports 3103. In one embodiment, the second segment has tenexternal ports 3104. In one embodiment, the first segment has 1, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more external ports 3103. Inone embodiment, the second segment has 1, 2, 3, 4, 5, 6, 7, 8, 9, 11,12, 13, 14, 15, or more external ports 3104.

Incorporating fluid contacting elements into the manifold, as describedabove, enables the design of systems where reusable sensors are mountedin the dialysis machine to which the manifold is mated while necessarilydisposable fluid contacting elements are separated out and placed in themanifold. To ensure proper readings and measurements are made, the fluidcontacting elements and reusable sensors need to be aligned. Mating andalignment between the manifold and dialysis machine is critical withrespect to positioning and pressure applied. Typically such matingprecision must provide for 0.001″ to 0.010″ tolerance in X, Y and Zdirections and apply a mounting force in the range of 10-100 PSI tooppose fluid forces with the manifold. Such critical positioning isaccomplished by means of specially designed positioning surfaces on themanifold registering with complimentary positioning surfaces on thedialysis machine. Required forces are delivered by analysis and designof dialysis machine structure to allow for X and Y positions and Zdirection deflections of less than about 0.001″ to 0.010″ under allfluidic and mechanical pressures developed within the manifold duringoperation. Because the manifold contains many structures on onemonolithic substrate such critical alignment need only be done onceserving to position all features of the manifold with all matingfeatures of the dialysis machine.

The mid-body channel size is nominally in the range of 0.190″ deep by0.190″ wide with 0.020″ radiuses at the bottom corners of the channel onthe mid-body side. The radius at the bottom corners of the channelshould be the maximum to prevent sinks from occurring under the channelwalls. These channel walls have valve and pressure diaphragm geometry onthe opposite side of the mid-body, which could be adversely affected bysink in these areas. In one embodiment, the fluid pathways are square.General design rule to prevent sink is that the wall thickness of a rib(channel wall in this case) should not be more than 50-60% of theadjacent wall, to which it is attached. The channel wall is 0.075″ andthe adjacent wall (main manifold structure) is 0.130″ resulting in 58%.The 0.190″×0.190″ dialysate channels transition to the 0.155″ tubingport through holes. This minimizes the accuracy required to align thefront cover to the mid-body and minimizes the potential for sinkscreated by the thicker walls which could affect sealing features on theopposite side of the mid-body. The same approach was taken foranticoagulant and infusate channels. Gentle curves are designed into thechannels to maximize laminar flow and minimize turbulent flow. In oneembodiment, the anticoagulant and infusate channels, as discussed below,measure 0.190″ deep by 0.100″ wide.

In one embodiment, the mid-body has alignment holes for assemblypurposes to ensure that both the front cover and back cover areaccurately aligned to the mid-body during the ultrasonic weldingprocess. The raised bosses around the alignment holes maximize contactwith the alignment pins of the welding fixture so that the plastic doesnot melt as easily due to friction. These bosses do not touch and arenot welded to ensure that the hole is patent.

FIG. 33 is a diagram detailing the fluidic circuit for the compactmanifold according to one embodiment of the present invention. Thefluidic circuit comprises four pump tube segments P1 3301, P2 3302, P33303 and P4 3304 in pressure communication with pumps within the topcontroller unit and pump shoes in the top controller unit door. Itfurther comprises five pressure membranes in pressure communication withpressure sensors S1 3305, S2 3306, S3 3307, S4 3308 and S5 3309, and anarea in thermal or optical communication with a temperature sensor S63310. In the embodiment illustrated in FIG. 33, three pairs ofmembranes, V1A and V1B 3311, V2A and V2B 3312 and V3A and V3B 3313, areintegrated into the manifold. The membranes function as valves when theyare occluded by a pin, member or protrusion from the controller unit.

Grouped in this manner the pairs of six one way valves, 3311 A,B, 3312A,B, 3313 A,B form three two way valve assemblies 3311, 3312, 3313. Thetwo-way valves provide greater flexibility in controlling theconfiguration of a circuit. When conventional two-way valves are used toocclude portions of a fluid pathway, they are typically configured toenable two different fluid pathways, one for a first valve state and onefor the second valve state. Certain valve embodiments, as disclosedbelow, used in combination with the valve membranes or pressure pointsintegrated into the manifold, enable more nuanced control, enabling thecreation of four distinctly different fluid flow paths.

Pump tube segments 3301, 3302, 3303, 3304 are bonded into the compactmanifold. A number of ports are provided in the manifold, which connectwith tubes external to the manifold to allow the flow of various fluidsin and out of the manifold. These ports are connected to various tubesin the blood purification system for carrying fluids as follows:

Port A 3315—blood to the dialyzer 3330;

Port B 3316—dialyzer output (used dialysate);

Port C 3317—blood from the patient;

Port D 3318—heparin for mixing in the blood;

Port E 3319—reservoir output (fresh dialysate);

Port F 3320—dialyzer input (fresh dialysate);

Port G 3321—dialyzer output (blood);

Port H 3322—patient return (clean blood);

Port J 3323—connects to prime and drain line;

Port K 3324—reservoir infusate input;

Port M 3325—infusate in from infusate reservoir;

Port N 3326—dialysate flow into sorbent.

In one embodiment, a tube segment, formed as a pathway molded into themanifold structure 3300, connects the fluid flow of heparin 3314,entering via Port D 3318, to the fluid flow of blood, entering via PortC 3317. The combined heparin and blood flow through port 3317 a, viapump segment 3301, and into port 3317 b of the manifold 3300. A pressuretransducer is in physical communication with a membrane 3305, formed inthe manifold structure 3300, which, in turn, passes the blood andheparin fluid through Port A 3315. Fluid flow out of the manifold 3300at Port A 3315 passes through dialyzer 3330, which is external to themanifold 3300. The dialyzed blood passes back into the manifold 3300through Port G 3321 and into a segment 3307, formed as a pathway moldedinto the manifold structure 3300 that is in physical communication witha pressure transducer. Fluid then passes from the segment through Port H3322 and into a patient return line.

Separately, dialysis fluid enters the manifold 3300 from a reservoir viaPort E 3319. Fluid in the reservoir has infusate in it, which firstenters the manifold 3300 via Port M 3325, passes through a segment,formed as a pathway molded into the manifold structure 3300, throughanother port 3325 a, through a segment 3302 in communication with apump, and back into the manifold 3300 via port 3325 b. The infusatepasses through a segment, formed as a pathway molded into the manifoldstructure 3300, and out the manifold 3300 at Port K 3324, where itpasses into the reservoir. The dialysis fluid which entered the manifoldvia Port E 3319 passes through a segment, formed as a pathway moldedinto the manifold structure 3300, through another port 3319 a, through asegment 3303 in communication with a pump, and back into the manifold3300 via port 3319 b.

The dialysate fluid passes into a segment, formed as a pathway moldedinto the manifold structure 3300, which is in physical communicationwith a pair of valves 3311. A segment, formed as a pathway molded intothe manifold structure 3300, passes the dialysate fluid to another pairof valves 3313. The segment is in physical communication with pressuretransducers 3308 and optional temperature sensor 3310. The dialysatefluid passes out of the manifold 3300 through Port F 3320, and into aline that passes into the dialyzer 3330.

A line out of the dialyzer 3330 passes fluid back into the manifold 3300through Port B 3316 and into a segment, formed as a pathway molded intothe manifold structure 3300, that is in physical communication with afirst pair of valves 3311, a second pair of valves 3312, and a pressuretransducer 3306. The used dialysate fluid passes out of the manifold3300 through port 3326 b, through segment 3304 in communication with apump, and back into the manifold via port 3326 a. A segment in fluidcommunication with port 3326 a is in physical communication withpressure transducer 3309 and passes fluid through Port N 3326 and to asorbent regeneration system.

The ports are designed for circuit tubing 0.268″×0.175″ tubing oranticoagulant and infusate tubing 0.161″×0.135″. Preferably, the tubingports are bonded with a suitable solvent.

It should be appreciated that the valves 3311, 3312, 3313 shown in FIG.33 can be positioned in different locations within the manifold.Referring to FIG. 86, valve 8611 (valve 3311 in FIG. 33) can bepositioned in the central vertical portion 8650 of the manifold 8600adjacent to and parallel to valve 8612 (valve 3312 in FIG. 33). Also onthe central vertical portion 8650 of the manifold 8600, which connectsthe top horizontal portion 8630 and bottom horizontal portion 8640together, is valve 8613 (valve 3313 in FIG. 33). Valve 8613 is on thebottom portion of the central vertical portion 8650 and positionedsubstantially below and centered between valves 8611, 8612.

In one embodiment, the 2-way valves operate by having valve actuators,which are mounted on the instrument, compress an elastomeric diaphragmover a volcano seal to prevent dialysate flow through its respectivepathway, as described in further detail below. The volcano seal openingis approximately 0.190″ diameter to match the channel geometry. Thecross-sectional pathway through the interior of the valve is at leastequivalent to 0.190″ diameter when valves are open. When the valve is inthe closed position the valve actuator and elastomeric diaphragm consumemost of the fluid path space around the volcano seal minimizing thepotential for air entrapment. There are raised plastic features on themid-body that minimize dead space within the fluid path as well as helpprevent the diaphragm from collapsing around the center fluid path undernegative pressure conditions. The elastomeric diaphragm has an o-ringfeature around its perimeter that fits into a groove on the mid-bodysurface. The o-ring is compressed between the mid-body and back cover toform a fluid tight seal. The design provides for approximately 30%compression on the o-ring. The 2-way valves control the direction ofdialysate flow through the manifold.

The manifold contains structures that allow for fluid pressuremonitoring across diaphragms through the use of sensors in theinstrument. Fluid is allowed to flow from channels on the front coverside of the mid-body through inlet and outlet holes underneath thediaphragm on the back cover side. The cross-sectional pathway throughthe interior of the pressure sensing structure is at least equivalent to0.190″. The interior pathway is designed to minimize air entrapmentwhile providing adequate fluid contact with the diaphragm. Theelastomeric diaphragm has an o-ring feature around its perimeter thatfits into a groove on the mid-body surface. The o-ring is compressedbetween the mid-body and back cover to form a fluid tight seal. Thedesign provides for a 30% compression on the o-ring.

The valves and diaphragms can be made from a variety of differentmaterials and by different processes. In one embodiment, the elastomericcomponents are made from silicone. In another embodiment, theelastomeric components are made from a variety of thermoplasticelastomers. Two shot molding may be used to attach the valves anddiaphragms to the back cover. Two shot molding of valves and diaphragmswould remove the need to individually assemble these parts into themanifold therefore reducing labor costs and improving quality of themanifold assembly.

Pumping components in the manifold design have been defined as PVCheader tubing. These headers combined with the rotary peristalticpumping system of the instrument provide the flow of blood, dialysate,and infusate. The circuit tubing material for dialysate, infusate, andanticoagulant is preferably kink resistant, such as the tubing referredto as Colorite, Unichem PTN 780, (80 A durometer) extruded by Natvar,and all TEKNIplex companies. The tubing dimensions for the dialysatelines range from 0.268″×0.189″ to 0.268″×0.175″.

In order to bring manifold segments into effective thermal, optical orpressure communication with one or more sensors through elasticmembranes, it is important to create a sufficiently proximate exposureof the fluid flow to the sensing apparatus. One way of doing so is shownin FIG. 34. Manifold segment 3400 receives a fluid flow 3410 that iscaused to move upward due to the blocking and redirecting position of aprotrusion, member, or other structure 3408 within the fluid path 3410.The fluid moves upward and is concentrated in between the membrane 3405and structure 3408, thereby enabling improved sensing. However, such anembodiment has the potential of resulting in blood clots forming inbends 3401, 3415 or occlusions caused by the adherence of the base 3406of membrane 3405 to the top 3407 of structure 3408 due to negativepressure.

Referring now to FIGS. 35A and 35B simultaneously, to minimize thepotential of blood clots or occlusions, it is therefore preferred thatthe structure of the manifold segments 3500 that are in thermal, opticalor pressure communication with one or more sensors through elasticmembranes 3505, also referred to as sensing segments, are designed in amanner that avoids creating sharp turns, bends, or U-shaped paths whichcould increase the likelihood of clotting or occlusions, yet stillprovide sufficient contact between flowing fluid and a sensor locatedover or proximate to the segment. Referring to FIGS. 35A and 35B, theinternal fluid pathway 3515 is now defined by a top surface comprising amembrane 3505 through which a sensor can be placed in thermal, opticalor pressure communication occurring through pathway 3515 and a bottomsurface defined by a) a first upward sloping wall 3525 that decreasesthe height of the pathway 3515 from a first height to a second heightalong the length of the wall 3525, b) a planar segment 3526 thatmaintains the same pathway height 3515 at the second height, and c) adownward sloping wall 3527 that increases the pathway 3515 height acrossthe length of the wall 3527 from a second height down to the firstheight again. The angled inclination/declination of the walls 3525, 3527cause the fluid pathway 3515 to narrow. Concurrently, however, the widthof the segment, defined by the angled walls 3525, 3527 and planarsegment 3526, widens relative to the manifold portions before and afterthis sensing segment. The sensing segment's height decrease and widthincrease relative to the manifold segments before and after the sensingsegment provides for a substantially constant velocity of fluid, therebyavoiding velocity changes that could hemolyze the blood, eliminatingdead spaces, and maintaining a low Reynolds number, while stillproviding the requisite contact area for the flexible membrane 3505,through which sensors conduct measurements. In one embodiment, one ormore posts 3535 are incorporated into the fluid pathway 3515, atop theplanar surface 3526, and below the membrane 3505 to prevent a completecollapse of the membrane 3505 due to negative pressure.

As would be appreciated from the above discussion, the blood anddialysis circuits of the manifold may be defined by a single piece ofmolded plastic, rather than a plurality of plastic components that arewelded together. However, when the blood and dialysis circuits aredefined by a single unitary piece of material, certain challenges arise.In particular, ports 3317 b, 3317 a, 3319 b, 3319 a, 3325 a, 3325 b,3326 a, and 3326 b in FIG. 33 are challenging to cost-effectively andreliably mold if the cylindrically shaped protrusions defining each portextend directly perpendicular from the manifold surface or, stateddifferently, are angled at substantially zero degrees from the side ofthe portion of the manifold to which the cylindrical protrusion isattached. If the ports are manufactured in a fully perpendicularconfiguration, the pins from the molding machine cannot be readilyremoved. Referring to FIGS. 33 and 36 simultaneously, it would bepreferred to manufacture ports 3317 b, 3317 a, 3319 b, 3319 a, 3325 a,3325 b, 3326 a, and 3326 b by having the cylindrical protrusion definingthe port structure 3655 be angled relative to the side of the manifold3645 to which the protrusion 3655 attaches, as defined by surface 3675.Therefore, in one embodiment, the internal manifold ports will be at anangle relative to the manifold surface. This angle further reducesstress on any pump tube segment which is inserted between the two angledports. It further positions the pump tube segment to be in a slightlycurved, bent, or otherwise non-linear shape to better conform to a pumpheader contact surface. In one embodiment, an angle, which is defined bya line normal to the center of the angled port and a line normal to theside of manifold, is less than 20 degrees and preferably less than 10degrees. In one embodiment, the angle is approximately 10 degrees. Inone embodiment, the internal manifold ports 3317 b, 3317 a, 3319 b, 3319a, 3325 a, 3325 b, 3326 a, and 3326 b are manufactured at theaforementioned angle while the remaining ports are at an angleapproximately equal to zero. In another embodiment, the protrusions3655, while described as cylindrical, have interior areas or volumes3753 in which the base 3754 is substantially planar and not curved whilethe rest of the internal structure defining the volume 3753 remainscurved 3756, as shown in FIG. 37. In another embodiment, all the portsor fluid pathways have interior areas or volumes 3753 in which the base3754 is substantially planar and not curved.

Another embodiment of a manifold is shown in FIGS. 38 to 40, with bloodand dialysate flow paths molded in a single compact plastic unit. In oneembodiment, the manifold 3800 is an easy to assemble compact plasticunit that has built-in molded blood and waste flow paths. Optionally,the sensors, pumps and hemofilter cartridges can also be integrated withthe compact plastic unit by insertion into concave moldings in the unit.In one embodiment, the dialysis system of the present invention iscapable of operating more than 8 hours per treatment and for up to 72hours continuously. It should be appreciated that fluid flows in and outof the manifold through defined inlet and outlet ports, such as to andfrom external pumps, to a waste UF reservoir, or to a patient returnline.

FIG. 39 shows a modular assembly of a manifold 3900 in one embodiment ofthe present invention. Pumping section 3930 comprises blood and wastepumps 3903, 3913 respectively. Module 3940 comprises molded flow paths3942 for blood and ultrafiltrate wastes and a hemofilter module 3950comprising a hemofilter cartridge 3908. This modular design allows quickand easy assembly of various modules into a single compact structure.

FIG. 40 shows an enlarged view of a mid-body module 3940 of FIG. 39. Inone embodiment, mid-body module 4040 comprises built-in molded flowpaths 4041 for carrying blood and waste. Connection ports 4042 are alsomolded into the mid-body module for connecting (via luer connectors andtubing) to pumps at one end of mid-body module 4040 and to a hemofiltercartridge at the other end of mid-body module 4040.

Referring back to FIG. 38, blood is drawn into the manifold 3800 viablood inlet port 3801 and molded flow path 3802 using a blood volumetricpump 3803 in pressure communication with a manifold tube segment. Bloodvolumetric pump 3803 pumps blood into hemofilter cartridge 3808 via themolded flow path 3804. Inlet pressure sensor areas 3806, 3807 are alsointegrated into manifold 3800 in molded flow paths 3802, 3804.

Referring back to FIG. 38, waste from the permeate region 3809 is drawnout by waste volumetric pump 3813 through molded flow path 3814, which,in one embodiment, has an integrated pressure sensor area 3815 locatedin-line of flow path 3814. The waste is pumped through molded flow path3816, which, in one embodiment, has an integrated blood leak detectorarea 3817 and waste flow meter 3818, in-line with flow path 3816 leadingout of the manifold 3800 through a waste outlet port 3819.

In one embodiment, the hemofilter cartridge 3808 is disposable and canbe removably integrated into the corresponding molded concavity in themanifold 3800 to complete the ultrafiltration circuit. The manifold 3800also provides an interface to a redundant pinch valve to prevent airfrom entering the patient's vascular system. The pinch valve is designedsuch that it is in a closed (occluded) position when no electrical poweris applied.

The molded flow paths 3802, 3804, 3810, 3814 and 3816 define the bloodand ultrafiltrate flow circuits of the manifold 3800. In one embodiment,these flow paths comprise disposable tubing and a plurality ofinterfacing components, such as joints, that are suitable for blood andultrafiltrate contact for at least 3 days. The joints preferably aredesigned to have at least 5 lbs. strength and seal to 600 mmHg (that is,greater than hemofilter maximum trans-membrane pressure). In oneembodiment, the blood set tubing corresponding to flow paths 3802, 3804and 3810 have suitable length and internal diameter for supplying ablood flow of 50 ml/minute. In one embodiment the prime volume of theblood set tubing, including the hemofilter, is less than 40 ml. Theblood set tubing interfaces with the blood volumetric pump 3803. Bloodpump 3803 tubing, in one embodiment, is of Tygon brand, formulationS-50-HL, size ⅛″ ID× 3/16″ OD× 1/32″ Wall.

Similarly, in one embodiment, the ultrafiltrate set tubing correspondingto flow paths 3814 and 3816 are capable of supplying an ultrafiltrateflow of 500 ml/Hr (8.33 ml/minute). The ultrafiltrate set tubing alsointerfaces with the waste volumetric pump 3813. Waste pump 3813 tubing,in one embodiment, is of Tygon brand, formulation S-50-HL, size 3/32″ID× 5/32″ OD× 1/32″ Wall.

Since the manifolds of the present invention comprise molded flow pathsfor blood, dialysate, waste fluids, and substitution fluids, the entireflow path can be easily manufactured as portable composite manifolds.The manifolds are also easy to handle since all flexible tubing outsidethe manifolds are attached on one side of the manifolds. Use ofmanifolds with built-in molded flow paths enhances fail-safe treatmentas the chances of disconnection, misassembly and leakage are minimizedin comparison to prior art systems that use a myriad of flexible tubing.Use of the novel manifolds also enhances ease of use leading to enhancedportability.

In one embodiment the dialysis manifolds are standalone compact unitssuch that they can be individually and separately used to process bloodfrom a patient. In another embodiment the two manifolds are connectableto each other to function as a dual stage blood processing system. Inone example, blood is drawn from an arterial site in a patient andpassed through a dialyzer where a large amount of waste fluid isconvected out. The manifold is used to return an equal amount of fluidback to the blood, before the blood is reinfused. The manifold measuresand dumps the waste fluid into a waste bag.

As known to persons of ordinary skill in the art, the hemofilter, ordialyzer, cartridge 3808 comprises a hollow tube further comprising aplurality of hollow fiber tubes whose walls act as a semi-permeablemembrane. The plurality of semi-permeable, hollow fiber tubes divide thehemofilter cartridge 3808 into blood flow regions 3805 within the hollowfiber tubes and a filtrate or permeate region 3809 outside the hollowfiber tubes. As blood passes through blood regions 3805, plasma waterpasses across the semi-permeable membranes of the hollow fiber tubes.The hemofilter cartridge 3808 is a small hemofilter. More concentratedblood flows out from the cartridge 3808 through molded flow path 3810and out of the manifold 3800 through a blood outlet port 3811. An airdetector area 3812 is also integrated into blood return flow path 3810.

The following are exemplary physical specifications of a hemofilter, ordialyzer, 3808 in accordance with one embodiment of the presentinvention:

Membrane Surface Area (m²) ≦0.1 Prime Volume (ml) ≦10 Molecular Weightcut-off (Daltons) 65,000 Pressure Drop3 (mmHg) ≦50 (Qb = 50 ml/minMaximum Transmembrane ≧500 Pressure (mmHg) Overall Unit Length (cm)12-15 Filtration rate 8-10 ml/min @100 mm Hg @ 50 ml/min Qb TubingConnections Blood Male Luer Filtrate Slip fit (straight) SterilizationETO or gamma Membrane Material Polysulfone (preferred) Housing materialPolycarbonate Potting material Polyurethane Sieving coefficients Urea1.00 Creatinine 1.00 Vit B12 0.98 Middle molecule/size ≧0.20 17,000Albumin ≦.03

During dialysis treatment, a patient or healthcare provider installs oneof the above described manifolds in the dialysis machine. Referring toFIG. 41A, the dialysis machine 4101 has a front door 4103 which can bewidely opened to install the disposable components. For installation,the manifold 4104 simply needs to be inserted in the space provided forthe purpose in the dialysis unit 4101, as previously discussed above.Installing the dialyzer 4102 also involves a simple insertion in adesignated recess. The front door 4103 is provided with pump shoes 4105that makes loading of disposable components very easy, as no pump tubingneeds to be thread between roller and shoes. Further, this arrangementallows installing the dialyzer 4102 and the manifold 4104 in a mannerthat ensures proper alignment against non-disposable components such aspressure readers, sensors, and other components. This packaged, simpleapproach enables easy disposables loading and cleaning of the system. Italso ensures that the flow circuitry is properly configured and readyfor use.

When the front door is closed, the manifold tubing becomes sandwichedbetween the pump shoes of the door and the pump rollers of the dialysismachine. The surfaces of the pump shoes are curved to conform with theshape and action of the pump rollers. In this configuration, the tubingmay veer back and forth across the surface of, and onto the edges of,the pump roller. This lateral slippage causes the tube to wear down andcan lead to failure. FIGS. 41B and 41C are side views of one embodimentof a modified pump shoe 4105 with elevated side walls 4110. The elevatedside walls 4110 encapsulate the tube and prevent it from physicallycontacting the pump roller edges, thereby prolonging the life of thetubing. The inner surface of the pump shoes have a curvature thatmatches the curvature of the pump roller being used. In one embodiment,both the top side walls 4110 and the top inner surface 4115 of the pumpshoe 4105 have the same degree of curvature. In another embodiment, thetop of the side walls 4110 and the top of the inner surface 4115 of thepump shoe 4105 have different degrees of curvature.

FIG. 41D is an oblique side view illustration of another embodiment of amodified pump shoe 4105 with elevated side walls 4110. Referring to FIG.41C, the elevated side walls 4110 are secured to the pump shoe 4105 withtwo screws 4140 that fixedly attach the walls 4140 to the shoe 4105 atthe base of the shoe 4105. In one embodiment, two screws are used tosecure each wall 4110 to each side of the pump shoe 4105. In thepictured embodiment, the angular portion of the elevated side walls 4110and the top of the inner surface 4115 of the pump shoe 4105 have thesame degree of curvature. In various embodiments, the height h of theside wall 4110 that extends above the inner surface 4115 of the pumpshoe 4105 is in a range between 0.060 and 0.095 inches.

FIG. 41E is an oblique top down view illustration and FIG. 41F is across-sectional illustration of multiple embodiments of modified pumpshoes 4105 a, 4105 b, 4105 c, each with elevated side walls 4110 a, 4110b, 4115 c of varying thickness based on the diameter of the pump tubingin use. In each of the embodiments, as seen in FIG. 41E, each side wall4110 a, 4110 b, 4110 c is secured to each pump shoe 4105 a, 4105 b, 4105c with two screws 4140. As can also be seen in FIG. 41E, the elevatedside walls 4110 a, 4110 b, 4110 c and the inner surfaces 4115 a, 4115 b,4115 c of each pump shoe 4105 a, 4105 b, 4105 c have the same degree ofcurvature. In addition, as can be seen in both FIGS. 41E and 41F, theelevated side walls 4110 b, 4110 c of the last two embodiments of pumpshoes 4105 b, 4105 c also extend inwardly over the inner surfaces 4115b, 4115 c of the pump shoes 4105 b, 4105 c.

Referring now to FIG. 41F, multiple embodiments of modified pump shoes4105 a, 4105 b, 4105 c with varying dimensions can be seen. Referring topump shoe 4105 a, the pump shoe 4105 a has an overall width of 0.850inches, including side walls 4110 a. The inner surface 4115 a of thepump shoe 4105 a has a width of 0.700 inches and the side walls 4110 aeach have a width of 0.075 inches. The side walls 4110 a have a heightthat extends 0.095 inches beyond the inner surface 4115 a of the pumpshoe 4105 a. The side walls 4110 a do not extend inwardly over the innersurface 4115 a of the pump shoe 4105 a. Modified pump shoe 4105 a isintended for use with a pump roller 4150 a with a width of 0.805 inches.In one embodiment, the rolling surface of the roller 4150 a ispositioned 0.126 inches away from the inner surface 4115 a, and 0.031inches away from the elevated side walls 4110 a, of the pump shoe 4105a.

Referring to pump shoe 4105 b, the pump shoe 4105 b has an overall widthof 0.850 inches, including side walls 4110 b. The inner surface 4115 bof the pump shoe 4105 b has a width of 0.580 inches and the side walls4110 b each have a width of 0.135 inches at the inner surface 4115 b.The side walls have 4110 b a width of 0.075 at the base of the pump shoe4105 b. The side walls 4110 b have a height that extends 0.060 inchesbeyond the inner surface 4115 b of the pump shoe 4105 b. The side walls4110 b extend inwardly over the inner surface 4115 b of the pump shoe4105 b by 0.060 inches on each side. Modified pump shoe 4105 b isintended for use with a pump roller 4150 b with a width of 0.705 inches.In one embodiment, the rolling surface of the roller 4150 b ispositioned 0.101 inches away from the inner surface 4115 b, and 0.041inches away from the elevated side walls 4110 b, of the pump shoe 4105b.

Referring to pump shoe 4105 c, the pump shoe 4105 c has an overall widthof 0.850 inches, including side walls 4110 c. The inner surface 4115 cof the pump shoe 4105 c has a width of 0.330 inches and the side walls4110 c each have a width of 0.260 inches at the inner surface 4115 c.The side walls 4110 c have a width of 0.075 at the base of the pump shoe4105 c. The side walls 4110 c have a height that extends 0.060 inchesbeyond the inner surface 4115 c of the pump shoe 4105 c. The side walls4110 c extend inwardly over the inner surface 4115 c of the pump shoe4105 b by 0.185 inches on each side. Modified pump shoe 4105 c isintended for use with a pump roller 4150 c with a width of 0.705 inches.In one embodiment, the rolling surface of the roller 4150 c ispositioned 0.108 inches away from the inner surface 4115 c, and 0.048inches away from the elevated side walls 4110 c, of the pump shoe 4105c.

FIG. 41G is a side view illustration of one embodiment of the modifiedpump shoe 4105 with elevated side walls 4110 of FIGS. 41B and 41C and apump roller 4120, depicting a length of tubing 4130 sandwichedtherebetween. As can be seen in FIG. 41G, as the tube 4130 is compressedby the pump roller 4120 against the pump shoe 4105, the tube remainsbelow the height of the elevated side walls 4110 of the pump shoe 4105.Lateral movement of the tube 4130 is bounded by the elevated side walls4110 and therefore the tube 4130 cannot veer back and forth across theedge of the pump roller 4120. The width of the pump roller is sized tofunction with the modified pump shoe inner surface and accommodate thetubing. The diameter of the tubing varies and is dependent upon its usein the dialysis machine and the roller width is sized to insure properpumping. In various embodiments, the roller width is within a range of0.705 to 0.805 inches.

Referring to FIG. 42, in one embodiment, the manifold 4202 is mounted onthe vertical front panel 4203 of the dialysis system 4201. The manifold4202 is accurately located on this panel 4203 by a plurality ofalignment mechanisms. The first alignment mechanism comprises aplurality of alignment pins in the panel 4203 that engage alignmentholes in the manifold 4202. The second alignment mechanism comprises atleast one latch that maintains the manifold 4203 in a specific mountedposition until the door 4206 is closed and the final accurate positionis obtained. In one embodiment, the back cover of the manifold 4202 hastwo designed-in tabs at top and bottom. These tabs latch the manifold4202 in a first holding position prior to the door 4206 closure andsubsequent placement of the manifold's 4202 accurate position. The tabsenable a latching mechanism that can be manually released or by balldetents that require forcibly removing the manifold 4202 by hand. Inanother embodiment, the latch mechanism comprises a spring loadedinsertion and release mechanism at the top of the back cover. Thismechanism had a connecting rod between the top latch and a bottom latch.When the release mechanism at the top was activated the bottom latchreleased as well.

The third alignment mechanism comprises contoured guides 4208 thatdirect the general position and configuration of the manifold 4202. Thecontoured guides 4208 are preferably shaped to mate with, match, orotherwise complement the physical structure of the manifold 4202. In oneembodiment, the guides 4208 are generally rectangular and configured tofit inside the space bounded by the sides of the first segment, secondsegment, and connecting segment of the manifold 4202, as describedabove. The fourth alignment mechanism comprises a door 4206 having atleast one spring loaded pressure plate 4205 that captures the manifold4202 between the door 4206 and front panel 4203, thereby applyingadequate pressure for valving and pressure sensing. The door 4206 alsoincludes four pressure shoes that apply adequate pressure to the pumpingcomponents for rotary peristaltic delivery of fluids.

It should be appreciated that one or more of the alignment mechanismscan be used, either alone or in combination, to achieve the requisitealigned and pressurized position for the manifold. It should further beappreciated that the alignment mechanisms are attached to the surface ofa recessed region within the dialysis device enclosure. The recessedregion comprises the front panel 4203 that is recessed relative to thedialysis device housing and is bounded by four walls (a first wall, asecond wall, a third and a fourth wall) that extends upward from thefront panel 4203 to meet and fixedly attach to the dialysis deviceenclosure. The recess is sufficiently deep and configured to receive thedoor 4206.

Sensing Systems

As stated above, the dialysis system, and particularly the topcontroller unit, comprises sensing systems that interact with portionsof the manifold, and particularly clear portions of the manifold ormembranes embedded in the manifold structure, to sense certainparameters or states, such as flow rates, temperature, pressure, thepresence of sodium, the presence of ammonia, pH levels, leaking blood,occlusion or air bubbles. For example, sensing for blood leakage, airbubbles, and/or occlusion is achieved by including optical sensors inthe dialysis machine which attach to, and around, pre-defined areas ofthe manifold. The manifold may comprise a plurality of tubing supportbrackets which facilitate accurately placing the circuit tubing intooptical sensors, such as Optek sensors, that are separately mounted inthe instrument when the manifold is installed and the door is shut. Thesensors provide means for detecting occlusion in the arterial line,blood leak in the blood line downstream of the dialyzer and airdetection in the venous blood line. The brackets restrain the tubing onone side of the sensor while the tubing port does the restraining on theother side of the sensor. These optical sensors are U shaped devicesinto which the tubing is forced when the manifold is installed. Thetubing support brackets provide support for the tubing so that all threeof these sensors are loaded with the same motion as loading themanifold, with no extra effort on the user's part. Sensing systems forflow rate, temperature, disconnection, central venous pressure, amongother systems, are further described below.

Flow Rate

In one embodiment, the dialysis system comprises a non-invasive ornon-contact type acoustic flow meter that has the ability to generate anacoustic signal directly in the fluid to be monitored without physicalcontact, thereby providing flow measurement with improved accuracy basedon the measurement of acoustic wave transit time. It is furthercontemplated the present flow meter can be used with one of the abovedescribed manifolds to non-invasively measure flow within the manifold.

FIG. 43 is a circuit diagram depicting an exemplary photo-acoustic flowmeter 4300. The fluid 4304 for which the flow rate is to be measured, iscarried by a fluid-bearing passageway 4305, such as a pipe, tubing, ormanifold segment, in the direction indicated by the arrow 4306. Thephoto-acoustic pulse flow meter 4300 comprises a light emitting system4310. In one embodiment, the system 4310 further comprises an LED orsolid state laser 4307, which is excited in a sinusoidal manner by asignal source 4308. In another embodiment, a Q-switched ruby laser maybe used in place of system 4310. Persons of ordinary skill in the artwould appreciate that any other suitable optical generation system knownin the art may be used for the purpose.

The optical generation system 4310 projects a beam 4309 into the fluid4304 through an optical aperture, or an optically transparent sectionformed in the wall of the passageway 4305 (i.e. manifold segment). Inone embodiment, the projected optical beam 4309 traverses through thefluid 4304 in a direction perpendicular to the direction of the axis4312 of the fluid-bearing passageway 4305. The optically transparentsection of tube 4305 should be transparent to the particular wavelengthof optical source 4310. The wavelength of optical source 4310 must beselected so that the light is readily absorbed by the fluid 4304, whoseflow rate the system is intended to measure. It should further beappreciated that, when the present system 4300 is used with a manifold,the optical generation system 4310 is preferably contained in thedialysis machine into which the disposable manifold is loaded andaligned with the manifold such that the generated optical beam 4309passes through a transparent section of the manifold.

As the optical beam 4309 passes into the fluid 4304, heat energyassociated with the optical beam is absorbed into the fluid. Theabsorption of heat occurs along the direction of the beam 4309 andcauses thermal fluctuations in the fluid 4304. These thermalfluctuations manifest as localized fluid heating and cause thermalexpansion in the fluid. As a result of this thermal expansion, anacoustic signal 4311 is produced. The nature of this signal, in terms ofpressure variations in the fluid 4304, replicate the waveform generatedin signal source 4308 used to power the optical signal generationelement 4307. This pressure variation propagates both downstream andupstream with respect to the location of the optical beam 4309 in thepassageway 4305.

As is known to persons skilled in the art, the acoustic signals receivedupstream and downstream by sensors 4313 and 4314 respectively will beout of phase with one another. The amount of the phase differencebetween the acoustic signals received upstream and downstream isdirectly proportional to the flow rate. It should be further appreciatedthat, when used in conjunction with a disposable manifold, the sensors4313 and 4314 are positioned proximate to the manifold tubing orembedded within the manifold tubing.

Accordingly, in one embodiment acoustic detectors T1 4313 and T2 4314are placed upstream and downstream respectively, equidistant from theoptical beam 4309, such that d1 4313 a and d2 4314 a are equal. Inanother embodiment, the upstream and downstream placement of 4313 and4314 need not be equidistant from 4309. Detectors T1 and T2 may beeither pressure transducers or acoustic transducers such as microphones.A microphone cartridge such as Model WM-55A103 manufactured by PanasonicCorporation is suitable for this application.

The detectors T1 4313 and T2 4314 interrogate the fluid flow to detectthe acoustic signal 4311 at the points where the detectors T1 4313 andT2 4314 are located. Interrogation occurs acoustically as the pressurevariations (sound) of acoustic signal 4311 are transferred through thewalls of conduit 4305 to sensors 4313 and 4314.

A first receiving amplifier 4315 is connected to the detector T1 4313and a second receiving amplifier 4316 is connected to receive the outputfrom the detector T2 4314. The outputs of the first and secondamplifiers 4315 and 4316 are connected to the inputs of first and secondphase sensitive detectors 4317 and 4318 respectively, through gaincontrol elements 4319 and 4320. One implementation of phase sensitivedetectors 4317 and 4318 is known in the art as a “lock in amplifier”.After the signals are processed by the amplifiers 4315, 4316 and phasesensitive detectors 4317, 4318, the outputs of 4317 and 4318 are passedthrough low pass filters 4321 and 4322 to eliminate high frequency noisecomponents, or ripples left over from the phase sensitive detectionprocess 4324, from the signals. The resultant outputs of filters 4321and 4322 are steady signals representative of the relative phase, withrespect to the original signal of generator 4308, of the acousticsignals detected by 4313 and 4314 respectively. Thus, the photo-acousticflow meter provides an indication of the phase angle of the upstream anddownstream acoustic signals, with respect to a reference signal.

After processing and phase detection by the phase sensitive detectorelements, the upstream and downstream phase angle signals are suppliedto addition/subtraction unit 4323. The output of theaddition/subtraction unit 4323 represents the phase difference betweenthe acoustic signal received upstream by the acoustic detector T1 4313and downstream by the acoustic detector T2 4314. This phase differencebetween these acoustic signals is directly proportional to the flow rateof the fluid and, as one of ordinary skill in the art would appreciate,can be used as the basis to calculate the actual flow rate or changes tothe flow rate. All means for calculating the flow rate comprise aprocessor and software algorithms for deriving the flow rate or changesin the flow rate, from at least the phase difference data. Therefore,the output of the addition/subtraction unit 4323 provides a measurementof the flow rate of the fluid 4304.

Thus, as described above, in one embodiment output voltage signals ofthe first and second low pass filers 4321 and 4322 are sampled and, inthe unit 4323, are subjected to a subtraction to determine a phasedifference signal indicative of the rate of flow of the fluid in thepassageway 4305. One of ordinary skill in the art would appreciate thatany other suitable means for computing the phase difference from theoutputs of the acoustic detectors may be employed. All such meanscomprise a processor and either hard coded or soft coded softwarealgorithms for calculating a phase difference.

As mentioned previously, the signal generated by the source 4308 acts asa reference signal for the upstream and downstream acoustic transducersT1 4313 and T2 4314. FIG. 44 depicts the reference signal 4400 agenerated by source 4308 of FIG. 43. FIG. 44 depicts the acoustic wavesignals, 4400 b and 4400 c respectively, after undergoing signalprocessing at the outputs of gain control amplifiers 4315 and 4316 ofFIG. 43, respectively.

In one embodiment, the photo-acoustic pulse flow meter is utilized tonon-invasively monitor the rate of flow of fluids in a dialysis systemsuch as a hemodialysis, hemofiltration and/or a hemodiafiltration systemknown to persons of ordinary skill in the art. The fluids for which flowrate measurement during dialysis is required are primarily blood anddialysate, in blood and dialysate circuits respectively; however one ofordinary skill in the art would appreciate that flow rate of otherfluids such as infusate or concentrate may also be measured with theflow meter of the present invention. Persons of ordinary skill in theart would also appreciate that the flow meter of the present inventionis also capable of indicating when there is a non-flow of fluid in aconduit/passageway.

Thus, referring back to FIG. 43, if the difference between signaloutputs of low pass filters 4321 and 4322 is null, this would imply thatthere is no flow of fluid. In a dialysis system application, thisdetection of non-flow of fluid is very useful, as it might be indicativeof a serious problem such as the disconnection of an arterial/venouscatheter connected to the patient.

In another embodiment, flow within the manifold can be measured by athermal flow meter. FIG. 56 illustrates the thermal fluid flowmeasurement device 5601 of the present invention installed with themanifold 5602 in the dialysis machine 5610. As mentioned earlier, themanifold 5602 has fluid flow paths or tubing circuit 5603 embeddedwithin. The dialysis machine 5610 has a front door 5620 which can beopened to install the disposable manifold 5602. Further, the front door5620 is equipped with pins 5621 that, when the door 5620 is closed, canmake contact with electrical points on the manifold 5602 to readinformation or provide electrical input.

The thermal fluid flow measurement device 5601 further comprises aseries of contacts 5611, 5612 and 5613. Operationally, as fluid (such asblood, dialysate or other fluids) flows during dialysis through thefluid flow path 5603, it passes the first contact 5611 which is embeddedin the plastic pathway. The contact 5611 makes electrical contact withan electrical source, which in one embodiment is a pin 5621 on themachine front door 5620. The electrical source or pin is controlled by acontroller in the dialysis machine 5610. The electrical source providesan electrical stimulus to the contact 5611, which acts to micro heat thecontact based on a sine-wave method.

In one embodiment, the micro heating process effectuates a temperatureincrease between 0.1 and 1.0 degrees Celsius in the fluid beingmeasured. This is effectuated by means of micro heaters located at thefirst contact 5611, which produce heat on receiving the electricalstimulus. Micro heaters for the thermal fluid flow measurement device ofthe present invention can be manufactured using any design suitable forthe application. In one embodiment for example, the micro heater is madeup of 10 turns of 30 g copper wire wound around a pin located at thefirst contact position 5611.

As the contact 5611 gets micro-heated, the resulting thermal energy actsto create a thermal wave, which propagates downstream from the firstcontact 5611. A plurality of contacts, which in one embodiment are twoin number—5612 and 5613 are located downstream from the first contact5611, and are used to measure the time of flight of the thermal wave.The measured phase of the wave is then compared with the initial wavegenerated by the first contact 5611. The phase difference thusdetermined provides an indication of the flow rate.

FIG. 45 illustrates one embodiment of a flow meter 4500 a with probesthat can be used for flow measurement. A channel 4501 a encompasses avolume 4502 a through which fluid, such as water or saline solution (0.9N) 4503 a flows. In one embodiment, the channel has a height in therange of 1 mm to 5 mm (preferably 3 mm), a width in the range of 3 mm to13 mm (preferably 8 mm), a length in the range of 10 mm to 100 mm(preferably 50 mm), a channel area in the range of 3 mm² to 65 mm²(preferably 24 mm²), and/or a hydraulic diameter in the range of 1.5 mmto 7.22 mm (preferably 4.36 mm).

The direction of the fluid flow is shown by arrow 4504 a. An excitationprobe 4505 a is positioned proximate to a receiver probe 4506 a. Therelative distance of the probes is an important feature of the design,as the excitation frequency at which the electrical stimulus needs to bedelivered by the excitation pin or probe 4505 a depends on the spacingbetween the probes 4505 a and 4506 a. In one embodiment, the excitationprobe and receiver probe are positioned less than 2 inches, preferablyless than 0.8 inches, and more preferably approximately 0.6 inches, orapproximately 15 mm, from each other. In this embodiment, excitation andmeasurement only requires two contacts, each contact having a contactsurface 4507 a. One of ordinary skill in the art would appreciate that,in such a case, only two contact points would be required, rather thanthree, as shown above relative to a disposable manifold and dialysismachine.

An excitation pin or probe 4505 a is embedded in the channel 4501 a andacts to provide a thermal stimulus (in the form of a thermal wave) tothe flowing fluid, which is then sensed and measured by the receivingprobe 4506 a. In one embodiment, the body diameter of the pin or probeis in the range of 0.03 inches to 0.15 inches (preferably 0.08 inches),the diameter of the top contact surface is in the range of 0.025 inchesto 0.2 inches (preferably 0.125 inches), and is made of gold platedbrass or any other material having a density of approximately 8500kg/m³, a thermal conductivity of approximately 1.09 W/mK and/or aspecific heat of approximately 0.38 J/KgK.

In one embodiment, the bodies of both the excitation pin or probe 4505 aand the receiving pin or probe 4506 a are molded into the manifold (suchthat the pin or probe is not in physical contact with the fluid and itstop contact area is exposed to one surface of the manifold). The body ofthe pin or probe is centered in the cell and fluid passes by it. The topof the pin is exposed so a spring loaded contact, from the instrumentpanel, can make thermal contact, thereby enabling the transfer ofthermal energy between the spring loaded contact and the contact surfaceof the pin.

For example, referring to FIG. 45, a side view of one embodiment of thethermal flow meter 4500 b of the present invention is shown with thecontact surface 4507 b exposed so that a spring loaded contact from theinstrument panel of the dialysis machine (shown in FIG. 56) can makethermal contact and thermal energy can be exchanged between the springloaded contact and the excitation pin or probe 4505 b. A channel 4501 bencompasses a volume 4502 b through which fluid 4503 b flows. Thedirection of the fluid flow is shown by arrow 4504 b. An excitationprobe 4505 b is positioned proximate to a receiver probe 4506 b, each ofwhich has a contact surface 4507 b.

FIG. 45 further shows thermal flow meter 4500 c from the end of the flowchannel 4501 c, which contains a volume 4502 c through which fluid 4503c flows. Here, only the receiver probe 4506 c and its contact surface4507 c are shown. In one embodiment, the receiving contact or pin 4506 chas a structure similar to that of the excitation pin 4505 b and its top4507 c is also exposed. In one embodiment, the receiver pin surface 4507c is also designed as a low thermal mass spring loaded contact. Theexcitation 4505 a as well as receiver 4506 a probes or pins are made upof a suitable material which has high thermal and electricalconductivity, which in one embodiment is gold plated brass.

In one embodiment, a low thermal mass spring loaded contact in theinstrument, such as a dialysis machine, is temperature controlled usinga heater and a thermistor. The temperature control function thengenerates a cosine temperature wave form in the probe which isreflective of the temperature wave created in the spring loaded contact.The resultant excitation signal characteristic of the excitation pin maybe defined as:

e _(s) =E _(s) cos(ωt), where ωt is the excitation frequency.

The thermal response of the receiver pin may be characterized by thefollowing equation:

r _(r) =R _(r) sin(ωt+θ), where ωt is the excitation frequency and Θ isthe phase.

One representation of the propagation of a thermal wave is shown in FIG.46. Referring to FIG. 46, the arrow 4601 represents the direction offlow of fluid (and hence the direction of propagation of a thermal wave)in a fluid pathway 4602 in a channel. Measurement contacts arerepresented by 4611, 4612 and 4613. Since the micro heater is locatedproximate to the first contact 4611, the thermal wave originates at thefirst contact, and then propagates towards the second and third contacts4612 and 4613 respectively, which are located downstream from the firstcontact 4611. The distance between the second 4612 and third 4613contacts is 4615.

FIG. 46 further illustrates exemplary wave measurements 4620 at thethree contacts 4611, 4612 and 4613. The thermal wave generated at thefirst contact 4611 is represented by the first curve 4621. Given thatthe flow is from left to right, this thermal wave will reach contact4612 at the second location slightly ahead of the time than when itreaches the contact 4613 at the third location. The outputs of thesecond and third contacts 4612 and 4613 are represented by the curves4622 and 4623, respectively.

The phase shift between the second 4622 and third 4623 signals can bemeasured by comparing the points of the zero crossing for each. Thedistance 4615 between the second 4612 and third 4613 contacts divided bythe time between the respective zero crossings (also called time offlight) is equal to the flow velocity of the fluid. Further, multiplyingthe computed flow velocity by the diameter of the fluid pathway yieldsthe volume flow rate.

The thermal wave can be monitored by using temperature sensors, which inone embodiment are constructed of thermistors, such as Cantherm, partnumber, CWF4B153F3470, and are placed in physical contact with contactslocated at the second and third positions. In one embodiment, thecontacts are monitored/measured using thermal measuring devices (whichare in contact with the two metal contacts) in the dialysis machineitself. This eliminates the need for separate temperature measuringdevices to be integrated in the manifold. It should be appreciated that,in a preferred embodiment, a dialysis machine, or non-disposableinstrument, contains a processor and a memory which record a) theexcitation frequency communicated to the spring loaded contact which,upon installation of a disposable manifold, physically communicates withthe contact surface of the excitation probe and b) the frequency of thetemperature wave sensed by the receiver probe and communicated, throughthe contact surface of the receiver probe, to a spring loaded contact inthe dialysis machine, or non-disposable instrument. The processorimplements the derivations, described herein, to determine thetemperature levels and changes based upon the above-listed stored data.It should be further appreciated that this temperature information isthen communicated to a display driver which causes the information to bevisually displayed, or audibly communicated, via a user interface.

In one embodiment, the detection circuit examines the phase shift bymixing the excitation signal and receiver signal, performing acomparison, and subjecting the result to a low pass filter in order toget the phase shift information. More specifically, in one embodiment,phase detection is accomplished by multiplying the excitation frequencyby the receiver signal. The results yield a signal with two components,one at twice the frequency and one being a DC signal proportional to thephase shift between the excitation reference signal and the receiversignal. This is represented by the following equation:

${{Phase}\mspace{14mu} {Detection}\text{:}\mspace{14mu} e_{s}r_{r}} = {\frac{E_{z}R_{r}}{2}\left\lbrack {{\sin \left( {{2\omega \; t} + \theta} \right)} + {\sin \; \theta}} \right\rbrack}$

Where e_(s) is the excitation signal, r_(r) is the receiver signal, ωtis the excitation frequency and Θ is the phase.

As described above, the present invention relies on a wave for time offlight measurement and not a thermal pulse. This method offers asignificant advantage because a thermal pulse disperses, resulting inuncertainty over where the pulse edge begins, and substantiallyincreases the measurement noise. Waves disperse as well but the phaseshifts of a sine wave, even after dispersion, remain more distinct.Therefore relying on sine wave for measurement introduces less noise.

Another advantage of the present invention lies in integrating thethermal flow rate sensor in the disposable manifold. The plastic used inthe manifold acts as a thermal insulator, which beneficially affectsmeasurements. As mentioned previously, in one embodiment spring-loadedprobes are used for the thermal flow measurement device, which makes itlow cost and disposable.

The design of the device of present invention is optimized in accordancewith three parameters: a) thermal excitation (frequency of the thermalinput signal), b) the expected flow rate (a slower flow rate requires adifferent frequency than a higher flow rate because a slower flow rateexperiences dispersion more), and c) amount and extent of thermaldispersion. In one embodiment, in order to minimize noise and improvedetection accuracy, one can set a key parameter as being constant, e.g.constant phase shift, constant frequency, or constant flow area.

In one embodiment, the constant phase shift method is implemented byusing a phase sensitive detector and a digitally controlled frequencygenerator. As described above, the time of flight causes a physicaldelay between the excitation probe and the receiver probe. At high flowrates the physical delay is small, while at low flow rates, the physicaldelay is large. Therefore, in order to maintain a constant phase shiftthe excitation frequency is controlled via feedback from the phasesensitive detector. A feedback loop is included in the system so thatimportant parameters such as excitation frequency can be dynamicallyadjusted such that the phase shift remains constant.

Referring to FIG. 53, a schematic of one embodiment of the presentinvention employing a constant phase shift mode of operation is shown.Liquid 5303 flowing through a channel 5301 passes by excitation probe5305 and receiver probe 5307, which are separated by a distance 5309, asdescribed above. In one embodiment, the channel 5301 is part of amanifold which is designed to be inserted into, and used within, adialysis machine. Once installed within the dialysis machine, thecontact surface of the excitation probe 5305 is made to thermallycontact a heater driver 5325 and the contact surface of the receiverprobe 5307 is made to thermally contact a temperature sensor 5330. Theheater driver 5325 and temperature sensor 5330 are in electrical contactwith a circuit, embodied in and/or integrated within, the dialysismachine.

On the excitation probe side, the circuit comprises a reference signalsource 5310 which transmits a signal having a phase θr to a summationdevice 5315, which also receives a signal input θm from a low passfilter, as described below. The two signals are summed, processed, orotherwise compared to yield an output which is transmitted to a voltagecontrolled oscillator 5320. The voltage controlled oscillator 5320outputs a signal, Rp where Rp=Kp sin(ωt), that is received by a heaterdriver 5325 and used to drive the heater driver 5325 to yield theexcitation wave which is thermally communicated to probe 5305.

The thermal wave propagates through the channel 5301 as a function ofthe fluid 5303 flow rate. The receiver probe 5307 thermally communicatesthe sensed thermal wave to the temperature sensor 5330. The thermalsensed wave can be expressed as a function as follows:

Es=Ks sin(ωt+θc).

As stated above, the temperature sensor 5330 is in electrical contactwith a circuit embodied within, or integrated into, the dialysismachine. The sensed thermal wave (Es) is communicated to a synchronousphase sensitive detector employing a multiplier component 5335, whichmultiplies the sensed thermal wave (Es) with an input signal from thevoltage controlled oscillator 5320 (Rn, where Rn=Kn cos(ωt)), yieldingan output signal EsRn. Output signal EsRn (which can be expressed asEsRn=(KnKs/2)[sin(2ωt+θc)+sin(θc)]) is input into the amplifier 5340 andamplified by constant K1. The amplified signal is then input into a lowpass filter 5345, which receives an input signal from the voltagecontrolled oscillator 5320. The input signal from the voltage controlledoscillator 5320 is used to vary the filter threshold, or cutoff, of thelow pass filter 5345. The output from the low pass filter 5345 (θm whichcan be expressed as a function of KnKsK1θc/2) is a signal that isindicative of the flow rate of the fluid, which can be derived by anymeans known to persons of ordinary skill in the art, and is communicatedback to said summation device 5315 for use in generating the referencesignal from the voltage controlled oscillator 5320.

FIG. 47 is a table which illustrates the range of excitation frequencythat is dynamically adjusted to maintain a constant phase shift.Referring to FIG. 47, the determination process takes into account thevalues of various parameters such as flow rate 4701, which variesbetween 25 to 600 ml/min and flow velocity 4702 which ranges from 17.36mm/s to 416.67 mm/s. Using a 15 mm value for probe separation 4703, theexcitation frequency 4705 will vary from ˜1.16 Hz @ 25 ml/min flow rateto 27.78 Hz @ 600 ml/min flow rate. The corresponding values of traveltime and receiver amplitude are detailed in rows 4704 and 4706,respectively. Note that receiver amplitude is maintained at zero for aconstant phase shift.

FIG. 48 illustrates the output of the phase sensitive detector plottedagainst time axis 4810. The various curves 4820 represent a series ofoutputs of the phase sensitive detector for different values of flowrate. The graphs in FIG. 48 have been plotted for the values given inthe table of FIG. 47; accordingly, the flow rate ranges from 25 to 600ml/min and the corresponding excitation frequency varies from ˜1.16 Hzto 27.78 Hz.

In another embodiment, phase shift may be allowed to vary while thefrequency excitation remains constant. Constant frequency excitation isemployed along with a phase sensitive detector, while a feedbackmechanism is not used. FIG. 49 illustrates a table detailing values ofvarious parameters when the excitation frequency 4906 is maintained at1.157 Hz. This value is for flow rate 4901 varying between 25 to 600ml/min and flow velocity 4902 ranging from 17.36 mm/s to 416.67 mm/s.While the probe separation 4903 is set at 15 mm, the correspondingvalues of travel time 4904 range from 0.0360 sec (for Harmonic 4905value of 1.000) to 0.864 sec. Varying phase shift is reflected in thecorresponding receiver amplitude values detailed in row 4907. Receiveramplitude 4907 is shown in the final row. FIGS. 50A and 50B illustratetwo sets of outputs (for the range of flow rates specified in FIG. 49)of the phase sensitive detector plotted against time axis.

Referring to FIG. 54, a schematic of one embodiment of the presentinvention employing a constant frequency mode of operation is shown.Liquid 5403 flowing through a channel 5401 passes by excitation probe5405 and receiver probe 5407, which are separated by a distance 5409, asdescribed above. In one embodiment, the channel 5401 is part of amanifold which is designed to be inserted into, and used within, adialysis machine. Once installed within the dialysis machine, thecontact surface of the excitation probe 5405 is made to thermallycontact a heater driver 5425 and the contact surface of the receiverprobe 5407 is made to thermally contact a temperature sensor 5430. Theheater driver 5425 and temperature sensor 5430 are in electrical contactwith a circuit, embodied in and/or integrated within, the dialysismachine.

On the excitation probe side, the circuit comprises a reference signalsource 5410, such as a sine generator, which transmits a signal having afrequency (e.g. at or about 1.17 Hz) to a heater driver 5425. The sinegenerator 5410 outputs a signal, Rp where Rp=Kp sin(ωt), that isreceived by a heater driver 5425 and used to drive the heater driver5425 to yield the excitation wave which is thermally communicated toprobe 5405. It is preferred that the excitation frequency is low enoughso at low flow rates the phase shift is less than 80 degrees. The sinegenerator 5410 also outputs a signal, Rn where Rn=Kn cos(ωt), that isreceived by a multiplier 5435 and low pass filter 5445, as furtherdescribed below.

The thermal wave propagates through the channel 5401 as a function ofthe fluid 5403 flow rate. The receiver probe 5407 thermally communicatesthe sensed thermal wave to the temperature sensor 5430. The thermalsensed wave can be expressed as a function as follows: Es=Ks sin(ωt+θc).The temperature sensor 5430 is in electrical contact with a circuitembodied within, or integrated into, the dialysis machine. The sensedthermal wave (Es) is communicated to a synchronous phase sensitivedetector employing a multiplier component 5435, which multiplies thesensed thermal wave (Es) with an input signal from the sine generator5410 (Rn, where Rn=Kn cos(ωt)), yielding an output signal EsRn. Outputsignal EsRn (which can be expressed asEsRn=(KnKs/2)[sin(2ωt+θc)+sin(θc)]) is input into the amplifier 5440 andamplified by constant K1. The amplified signal is then input into a lowpass filter 5445, which receives an input signal from the sine generator5410. The input signal from the sine generator 5410 is used to vary thefilter threshold, or cutoff, of the low pass filter 5445. The outputfrom the low pass filter 5445 (θm which can be expressed as a functionof KnKsK1θc/2) is a signal that is indicative of the flow rate of thefluid, which can be derived by any means known to persons of ordinaryskill in the art. It should be appreciated that the frequency cutoff ofthe low pass filter is approximately 1/20 of the frequency of theexcitation frequency. The low pass filter should attenuate the 2 wtsignal by at least 80 db.

FIG. 55 shows the relative phase shifts of signals generated in theconstant frequency mode with a low flow rate and a high flow rate. Anexcitation signal 5530 is generated at time 0. In a low flow ratescenario, the sensed signal 5520 is offset from the excitation signal5530 by a phase shift of θ_(LF) 5540 while, in a high flow ratescenario, the sensed signal 5510 is offset from the excitation signal5530 by a phase shift of θ_(hF) 5550.

Regardless of whether constant or varying phase shift method is employedfor measurement, using phase shift as the basis of flow measurement isadvantageous as compared to using amplitude, since amplitude can getaffected by external factors such as external temperature influences,which should not affect the phase shift.

In one embodiment, the non-invasive thermal fluid flow meter of thepresent invention provides a measurement range of 20 ml/min to 600ml/min. Besides the factors listed previously, other factors that areimportant for designing the thermal flow meter for optimum performanceinclude flow characteristics such as flow regime, maximum Reynoldsnumber and flow velocity; and physical characteristics of the flow cell,such as channel height, width and length.

FIG. 51 comprises a table delineating an exemplary set of designparameters optimized such that the flow regime is kept laminar andReynolds number 5109 is maintained under 2000, for a maximum flow rate5101 of 600 ml/min. For keeping the flow regime laminar, channelsize—including channel height 5102, width 5103, length 5104, area 5105and hydraulic diameter 5106 are optimized. Reynolds number 5109 iscomputed after taking into account values of flow velocity 5107,hydraulic diameter 5106 and properties of water 5108, such as density,dynamic viscosity and kinematic viscosity.

In one embodiment, the flow cell is designed for turbulent flow regimeinstead of laminar. Such a design of the flow cell entails a constantflow area, which in turn would involve the flow area being widenedaround the probes (which is reduced around the probes for laminar flow).When the area at the probes widens, the fluid increases in velocityaround the probes and the increased velocity causes the flow regime tomove into the turbulent regime.

FIG. 52 is a table illustrating another set of exemplary designparameters for the excitation and receiver probes, which in oneembodiment are sized to have a thermal time constant 5205 under 1millisecond for optimum performance. The factors taken into account forthis purpose are the material—which in this case is brass, and itsproperties 5201 such as density, thermal conductivity and specific heat,as well as convection coefficient 5204. Accordingly the size 5202 andexposed surface area 5203 of the probes is determined.

Temperature Sensing

As mentioned above, the compact manifold for the dialysis system alsoincludes a temperature sensor. In one embodiment, the temperature sensoris located in the reservoir assembly. However, the temperature sensormay also be located outside the reservoir assembly, and in suchembodiments, it can be integrated into the manifold.

There are three major approaches using temperature sensing which can beintegrated into the manifold. One of ordinary skill in the art wouldappreciate that variations are possible with each approach, withouteffecting any significant change in the overall design of the manifold.These approaches are discussed as follows:

High Conductivity Fluid Contact

In a high conductivity direct fluid contact approach, a metal disk isbuilt into the wall of the manifold with a thermistor or any othersuitable temperature sensor known in the art placed in contact with thedisk on the dialysis machine side, and with fluid on the patient side.Fluid temperature may thus be monitored through the metal disk.

Conventionally, the temperature is monitored by placing a thermistordirectly in the fluid stream. Use of a metal disk for monitoringtemperature in the present invention provides an advantage that lowersthe risk of contamination, and hence the need for cleaning of thethermistor is avoided.

A person of ordinary skill in the art would appreciate that a metal diskof any suitable metal, such as type 316 Stainless Steel, may be used forthe purpose. Further, a thermistor of any make appropriate for thecurrent application may be employed. An exemplary thermistor is partnumber 10K 3A1A manufactured by BetaTherm.

In one embodiment, the metal disk is for single patient use anddisposable, and the thermistor is part of the dialysis machine and isreused.

Medium Conductivity Fluid Contact

The pressure transducer membranes of the compact manifold are relativelythin and constructed of a medium thermal conductivity material.Thickness of typically 0.040″ is used and can vary from 0.005″ to 0.050″The thinner the material and the higher the thermal conductivity, themore accurately the pressure transducer membranes will transmittemperature of the dialysis fluid to the pressure transducer mountedinside the dialysis machine. By design they are in direct contact withthe pressure transducer on the machine side and the fluid on the patientside. Placing a suitable temperature sensor inside the pressuretransducer allows monitoring of the fluid temperature. Certain pressuretransducers known in the art already include a temperature sensor forcorrection of the transducer due to temperature drift. Such pressuretransducers with temperature sensing feature can be used for the purposeof the present application. An exemplary combinationpressure—temperature sensor is model MPT40 manufactured by MicronInstruments. Employing such a combination of sensors avoids directcontact of the fluid measured and reduces the number of components inthe manifold. This provides an alternative to the metal disk, as used inthe previous approach.

Indirect Optical Temperature Measurement

If the plastic wall of the manifold fluid path is of limited thickness,such as approximately 0.020″, then the plastic wall will equilibrate intemperature to the fluid inside the manifold. Under such conditions anon-contact optical temperature measurement can be made from outside ofthe thinned wall, and fluid temperature within can be determined. Anexemplary non-contact optical temperature sensor is part number MLX90614manufactured by Melexis. The non-contact approach provides the advantagethat it requires no additional parts in the manifold. The onlyrequirement is a thin section in the fluid path walls. This approachprovides low cost and still maintains single patient use safetyfeatures.

One possible implementation for an integral conductivity sensor in themanifold is as a conductivity cell with electrical pins contacting thedialysate fluid. The technical details of an exemplary conductivity cellare shown in FIG. 57. Referring to FIG. 57, the conductivity cell 5700comprises bias pins 5701 for applying a small, constant current to thefluid. Sensing pins 5702 detect the voltage in the fluid, wherein themagnitude of the detected voltage is dependent on the conductivity andtemperature of the fluid. The temperature is measured using a thermistor5703 placed next to the conductivity cell 5700. Alternately thetemperature can be determined by one of the means disclosed above.Knowing the values of the measured temperature and voltage at thesensing pins 5702, conductivity of the fluid can be determined.

The current applied through the bias pins 5701 can be DC or an AC signaland is generally in the 50-100 kHz frequency range. In one embodiment,the magnitude of the applied current is of the order of 10 mA. Sensingpins 5702 are generally depth positioned during manufacture of theconductivity cell, typically to a depth of +/−0.001 inch with calsolution in the cell. The thermistor 5703 has a typical accuracy of 0.5Deg C. The conductivity cell can be built into a dialysate fluid passageof the compact manifold by driving or molding in place conductive pins(bias pins and sensing pins) into the manifold body such that they comein contact with the dialysate but do not allow dialysate to leak out ofthe manifold.

Disconnection Detection

Embodiments of the disclosed dialysis system further incorporate anapparatus and method for the detection of disconnection in anextracorporeal blood circuit being used for any blood processingtreatment routine. Examples of blood processing treatment routinesinclude hemodialysis, hemofiltration, ultrafiltration, or apheresis.Vascular access for establishing an extracorporeal blood circuit istypically obtained by using a transdermal needle or a luer connectedcatheter. The disconnection apparatus and method uses the pressure pulseproduced by a patient's beating heart as an indicator of an intactneedle or catheter connection to the vasculature. The pressure pulseproduced by a patient's heart is small; more so, in the venous returnline of an extracorporeal blood circuit. In order to detect the smallpressure pulse the present invention uses cross correlation methodologywherein a reference cardiac signal is cross correlated to the pressurepulse signal.

FIG. 58 is a block diagram of a system 5800 for detecting a patient'sdisconnection from an extracorporeal blood circuit, in accordance withan embodiment of the present invention. System 5800 comprises anincoming arterial blood circuit 5802, a dialyzer 5804, a dialysatecircuit 5806, a patient pulse pressure transducer 5808, a patientcardiac signal generator 5815 for reference, a disconnect monitor 5820,a controller 5825 and a return venous blood circuit 5810. In variousembodiments of the present invention, blood drawn from a patient ispassed through the dialyzer 5804 via the arterial blood circuit 5802 andcleansed blood from the dialyzer 5804 is returned to the patient via thevenous blood circuit 5810. Contaminated dialysate expelled from thedialyzer 5804 is purified or regenerated within the dialysate circuit5806 and is pumped back into the dialyzer 5804. In various embodimentsof the present invention, cleansed blood is returned to a patient's bodyvia a transdermal needle or a luer connected catheter. Blood flow ratesin the return venous blood circuit 5810 are typically in the range of300-400 ml/min. It should be appreciated that any suitable dialysiscircuit can be deployed.

The pressure transducer 5808 measures the pressure pulse of a patientundergoing the blood processing treatment routine and communicates thepulse pressure substantially continuously to the disconnect monitor5820. In one embodiment the transducer 5808 is an invasive ornon-invasive venous pressure sensor located anywhere in the dialysisblood line (the incoming arterial blood circuit 5802 or the returnvenous blood circuit 5810). In another embodiment, the transducer 5808is an invasive or non-invasive venous pressure sensor locatedspecifically in a dialysis blood line between the dialyzer 5804 and thepatient, that is, in the return venous blood circuit 5810. Anon-invasive air bubble detector and/or pinch valve (not shown) areoptionally located between the transducer 5808 and the luer connectionto the patient. In an embodiment of the present invention, the pressuretransducer 5808 is located in close proximity to the needle or catheterinserted in the patient's body for providing vascular accesscorresponding to the return venous blood circuit 5810. The pressuretransducer 5808 is located in close proximity to the needle or catheterin order to preserve waveform fidelity. In other embodiments, thepressure transducer 5808 may be connected anywhere in the return venousblood circuit 5810. In an embodiment of the present invention, thepressure signal produced by the pressure transducer 5808 is analternating current (AC) signal which is not an accurate measure ofvascular pressure. Hence, the pressure transducer 5808 is not a highaccuracy transducer.

The reference signal generator 5815 communicates the patient's cardiacsignal substantially continuously to the disconnect monitor 5820 forreference. In an embodiment of the present invention, the referencecardiac signal is obtained from a plethysmograph connected to the samebody part (such as an arm) to which the needle or catheter supplyingprocessed blood to a patient is connected. In another embodiment of thepresent invention, the reference cardiac signal is obtained from afinger pulse sensor/oximeter. In various other embodiments of thepresent invention, the reference cardiac signal may be obtained via anelectro-cardiogram (ECG) signal, a real time blood pressure signal,stethoscope, arterial pressure signal from the blood withdrawal line,oximeter pulse signal, alternate site plethysmograph signal,transmissive and/or reflective plethysmograph signals, acoustic cardiacsignals, wrist pulse or from any other cardiac signal source known topersons of ordinary skill in the art.

The disconnect monitor 5820 detects a disruption in the return venousblood circuit 5810 caused by the disconnection of a needle or catheterfrom the body of a patient undergoing blood processing treatment. Todetect a disconnection, the monitor 5820 processes the patient pulsepressure transducer and cardiac reference signals. Persons of ordinaryskill in the art would appreciate that such disconnection may be causedby the needle or catheter being pulled out of the patient's body due toany reason such as a sudden movement of the patient. The disconnectmonitor 5808 is described in detail with reference to FIG. 59.Controller 5825 is any microprocessor known to persons of ordinary skillin the art. The function of the controller 5825 is to receive processedinputs from the monitor 5820 and accordingly trigger appropriateactions, when required.

Persons of ordinary skill in the art should appreciate that the pressuretransducer and reference signals are communicated to the disconnectmonitor 5820 through transmitters incorporated into the reference signalgenerator and pressure transducer. The transmitter can enable a wired orwireless communication to a corresponding receiver. Similarly, data fromthe disconnect monitor 5820 is communicated to the controller 5825through a wired or wireless connection. In one embodiment, such signalcommunication is enabled using an appropriate wired or wireless publicand/or private network such as LAN, WAN, MAN, Bluetooth networks, and/orthe Internet. Also, in one embodiment the disconnect monitor 5820 andcontroller 5825 are located in proximity to each other and to thepressure transducer 5808 and the cardiac reference signal generator5815. In an alternate embodiment, both or either of the disconnectmonitor 5820 and the controller 5825 are/is located remotely from eachother and/or from the rest of the components of the system 5800.

FIG. 59 is a block diagram illustration of an apparatus 5900 fordetection of a disconnection in a return venous blood circuit, inaccordance with an embodiment of the present invention. The disconnectmonitor 5900 comprises a pressure transducer receiver 5902, a referencesignal receiver 5904, and a cross correlation processor 5906. Thetransducer receiver 5902 and the reference signal receiver 5904 receiveinput signals from the pressure transducer 5808 and cardiac referencesignal generator 5815, respectively, of FIG. 58.

The pressure pulse signal obtained by the pressure transducer receiver5902 and the reference cardiac signal obtained by the reference signalreceiver 5904 are stored in a local memory and further fed to the crosscorrelation processor 5906, which in turn, computes a correlationbetween the two signals. The output of the processor 5906 is fed intothe controller 5825 of FIG. 58. If the output produced by the crosscorrelation processor 5906 indicates a correlation between the two inputsignals, it is inferred that the return venous blood circuit is intact.If the output produced by the cross correlation processor 5906 does notindicate a correlation between the two input signals, it is inferredthat the return venous blood circuit is broken due to a needle orcatheter pull out, and the controller 5825 of FIG. 58 triggersappropriate actions, such as sounding an indicative alarm and/orshutting down the dialysis system completely or partially.

Persons of ordinary skill in the art should note that the presentinvention envisages use of any cross correlation processor that links,corresponds, or otherwise creates a measurable, quantifiable, and/orpredictable relationship between the pressure transducer signal andreference signal. In one embodiment of the present invention crosscorrelation is performed by using a lock in amplifier, such as SR810Lock-In Amplifier manufactured by Stanford Research Systems, California.Various known techniques for cross correlation detection of very lowsignal to noise ratio systems, and cardiac signals may be incorporatedin the cross correlation processor 5906.

In various embodiments of the present invention, the cross correlationfunction, computed by the cross correlation processor 5906, is used tomeasure the similarities between the two input signals, i.e. thereference cardiac signal and the pressure pulse signal. Computation ofthe cross correlation function comprises computation of a sum of theproducts of corresponding pairs of points of the two input signals,within a specified time frame or window. The computation also takes intoconsideration any potential phase differences between the two inputsignals by including a lead or lag term. The mathematical formulacorresponding to a cross correlation function is represented as:

${r_{(12)}(j)} = {\frac{1}{N}{\sum\limits_{n = 0}^{N - 1}{{x_{1}(n)}{x_{2}\left( {n + j} \right)}}}}$

where N represents a number of samples, j represents a lag factor and x1and x2 represent the two input signals respectively.

FIG. 60 is a flow diagram showing exemplary steps of a method ofascertaining a patient's disconnection from an extracorporeal bloodcircuit, in accordance with an embodiment of the present invention. Inoperation, dialysis system software, comprising a plurality ofinstructions and executing on a processor, prompts a patient to firstattach a cardiac signal generator (such as a finger pulse oximeter) toobtain 6005 a reference signal. At this point the patient may or may notbe connected to a dialysis system. Thereafter or concurrent to capturingthe cardiac reference signal, the dialysis system software, comprising aplurality of instructions and executing on a processor, prompts apatient to connect to the system 5800 of FIG. 58 as a result of whichpatient pulse pressure transducer signal is also obtained 6010. Next, across correlation processor attempts to correlate 6015 the reference andtransducer signals. If no correlation can be achieved at start-up, inone embodiment, the patient is prompted to turn off 6020 all or certaincomponents or, in another embodiment, the controller 5825 of the system5800 of FIG. 58 does this automatically to lower noise level. Forexample, shutting off the pumps of the dialysis system can lower thenoise and make it easier to capture and correlate the two signals. Inanother embodiment, a cross-correlation is attempted beforenoise-generating system components, such as pumps, are turned on. Thus,lock down of a correlation is attempted before complete system start-upcan be completed. In one embodiment, if no correlation is locked down,an alarm is triggered, indicating the patient dialysis system may havean anomaly.

However, if a correlation is obtained, then that correlation issubstantially continually monitored 6025. If there is any deviation inthat correlation, an alarm is triggered 6030, indicating a possible leakor, optionally, the system is shut down (completely or partially) and anattempt to re-establish the correlated signal is attempted again. In oneembodiment, if the nature of the correlation changes or deviates beyondor within a predefined threshold, certain system components, such aspumps, are shut down and the cross correlation processor attempts tore-establish the correlation. If the correlation cannot bere-established, then an alarm is triggered. In another embodiment, ifthe nature of the correlation changes or deviates beyond or outside therange of a predefined threshold, certain system components, such aspumps, are shut down and an alarm is immediately triggered, before anyadditional attempt to re-establish the correlation.

This approach to monitoring disconnection provides certain distinctimprovements over the prior art. First, unlike the prior art, thepresent invention is responsive if the needle is just barely pulled outor if it is removed and pulled quite some distance from the insertionsite. Second, the present invention does not need any extra apparatusplaced at the insertion site, such as a moisture pad. Third, by crosscorrelating the patient's own cardiac signal, the false negatives aregreatly diminished. Fourth, the combination of pressure pulse sensingand cross correlation renders the present invention unique and capableof detecting low signal to noise ratio signals. Fifth, continuouslymonitoring the cross correlation status enables the system to detectsmall signal deviations which could potentially indicate adisconnection. Therefore, an apparatus and method for detection ofdisconnection in an extracorporeal blood circuit being used for anyblood processing treatment routine, is provided by the presentinvention.

Central Venous Pressure Monitoring

Embodiments of the dialysis system disclosed herein further incorporatemethods and systems for monitoring and controlling the ultrafiltration(UF) rate, such that the volume of fluid within a patient undergoingdialysis/ultrafiltration remains within a desired range. This inventionintegrates central venous pressure (CVP) monitoring into a dialysissystem and uses CVP measurements to control the rate of ultrafiltration(UF). CVP feedback data helps prevent over-removal of fluids as a safetymeasure and provides a means for titrating the UF rate for improvingtherapy.

CVP measurement entails measuring the average pressure present in thecentral venous line used for dialysis, thereby integrating CVPmeasurement with dialysis. In order to measure CVP, an appropriatecatheter needs to be inserted in the patient's body, such that the tipof the catheter is placed intrathoracically. FIG. 61 depicts anexemplary location of a central venous catheter for hemofiltration andCVP measurement. Referring to FIG. 61, a Central Venous Catheter (CVC)6110 is used to provide vascular access for UF. In this particularembodiment, the entrance site 6120 chosen for the CVC 6110 is below thecollarbone (clavicle) 6130, at the subclavian vein 6140. One of ordinaryskill in the art would appreciate that any other large vein in thepatient's body may be selected as an alternate site for inserting theCVC, while keeping its tip intrathoracic. The CVC 6110 passes through asubcutaneous tunnel 6150, and is secured with the help of a clamp 6160and a standard luer-lock 6170. Pressure at the tip of the CVC at theexit site 6180 is equal to the Central Venous Pressure.

In one embodiment of the present invention, the CVC 6110 is used foraccessing blood during hemofiltration, and the central venous pressuremay be measured using sensors inside the hemofiltration machine. In thiscase, no additional equipment is required for CVP measurement. Inanother embodiment, a dual lumen CVC is used for hemofiltration. In thiscase, the proximal lumen can be used for blood withdrawal and the distallumen (at the tip) can be used for returning blood. Either lumen or portcan provide a CVP measurement. In both cases, when a CVC is used forblood access, the system of present invention provides that prior totaking a CVP measurement, blood flow is momentarily stopped to enablethe accurate measurement of pressure. Therefore, in one embodiment, thepresent invention integrates into conventional dialysis machinesprogrammatic controls for stopping blood flow through the device basedupon a predetermined CVP measurement rate.

FIG. 62 is a block diagram illustrating the dialysis control system ofthe present invention. Referring to FIG. 62, a user interface 6210 isprovided that receives inputs from the user (clinician) indicating thepreferred frequency of CVP measurement and the preferred range of CVPvalues. These inputs are supplied to the central dialysis controller6220. The central dialysis controller 6220 is a programmable system thatcan be used to regulate CVP monitoring, and the rate ofhemodialysis/ultrafiltration based on the monitored CVP. Depending onthe frequency of CVP measurement determined by the user, the centraldialysis controller 6220 communicates a signal to the blood pump in thedialysis system 6230 to stop the blood flow whenever a CVP measurementis to be recorded. Following this, a CVP sensor in the dialysis system6230 takes the measurement and communicates it to the central dialysiscontroller 6220, which may transmit it to the user interface 6210 fordisplay. After a CVP measurement is complete, the central dialysiscontroller 6220 communicates another signal to the dialysis system 6230,causing the blood flow to resume. The central dialysis controller 6220also keeps track of the measured CVP values to determine if they are inthe user-defined range. A decrease in CVP below the defined range wouldindicate hypovolemia. In such a case, the central dialysis controller6220 halts the process of ultrafiltration, so that no additional fluidcan be removed until CVP is restored to the desired range. In oneembodiment the central dialysis controller 6220 titrates theultrafiltrate removal to the range of 2-6 mm Hg, which keeps the CVP inthe desired range.

The CVP monitoring and UF regulation system contemplates a wide range ofCVP measurement systems, integrated with conventional dialysis machines.Measuring CVP can be accomplished in a number of ways. In oneembodiment, CVP may be measured with a sensor located at the tip of anappropriate catheter. In another embodiment, CVP may be measured with adedicated pressure transducer located remote from the catheter, with thetransducer being held at the same level as the heart. FIG. 63 is anexemplary illustration of the latter embodiment. Referring to FIG. 63, acatheter 6310 used for accessing blood is shown. The catheter 6310 isplaced in the Central Vena Cava 6320. The pressure transducer 6330measures the central venous pressure at the heart level. The CVPmeasurement in this case is used to control the rate of hemofiltrationin the same manner as when a CVC is used.

In another embodiment, CVP is measured with a remote sensor inside thehemofiltration machine. Referring to FIG. 64, an exemplary blood circuit6400 with the provision of CVP measurement is illustrated. As bloodenters into the circuit 6400 from the patient, an anticoagulant isinjected into the blood using the syringe 6401 to prevent coagulation. Apressure sensor PBIP 6410 is provided which is used for the measurementof central venous pressure. A blood pump 6420 forces the blood from thepatient into the dialyzer 6430. Two other pressure sensors PBI 6411 andPBO 6412 are provided at the inlet and the outlet, respectively, of thedialyzer 6430. The pressure sensors PBI 6411 and PBO 6412 help keeptrack of and maintain fluid pressure at vantage points in thehemodialysis system. A pair of bypass valves B 6413 and A 6414 is alsoprovided with the dialyzer, which ensures that fluid flow is in thedesired direction in the closed loop dialysis circuit. The user canremove air at the port 6417 if air bubbles have been detected by sensor6418. A blood temperature sensor 6416 is provided prior to the airelimination port 6417. An AIL/PAD sensor 6418 and a pinch valve 6419 areemployed in the circuit to ensure a smooth and unobstructed flow ofclean blood to the patient. A priming set 6421 is pre-attached to thehemodialysis system that helps prepare the system before it is used fordialysis.

For taking CVP measurements, blood flow in the circuit 6400 is stoppedby stopping the blood pump 6420. At this point, the pressure in thecatheter used for accessing blood (not shown) will equilibrate, and thepressure measured at pressure sensor PBIP 6410 in the hemofiltrationmachine will be equal to the pressure at the catheter tip. This measuredpressure (CVP) is then used to regulate the rate of ultrafiltration andthe volume of fluid removed from the patient.

Thus, operationally, the system of present invention modifies aconventional dialysis system such that ultrafiltration is conducted at arate preset by the physician. Periodically, the blood flow is stoppedand the average CVP is measured using one of the various measurementmethods described above. In one embodiment, a safety mode is provided,wherein if CVP drops below a preset limit, hemofiltration isdiscontinued and an alarm sounded.

In another application, a hypervolemic patient such as a patient withCongestive Heart Failure (CHF) may be given ultrafiltration to removefluids. It is known in the art that while the ultrafiltration processremoves fluid from the blood, the fluid that is intended to be removedis located in the interstitial spaces. Further, the rate of fluid flowfrom the interstitial spaces into the blood is unknown. Without thesystem of present invention, a physician can only guess at theinterstitial fluid removal rate that will balance fluid removal from theblood stream with the fluid flow back into the blood from theinterstitial space, and sets the dialysis machine for that rate. In sucha scenario, constant monitoring on the part of the physician is requiredto make sure that the fluid removal rate does not over- or under-hydratethe patient. With the system of present invention, a physician canpre-set the total amount of fluid he wants removed—typically computedfrom patient weight, and the minimal average CVP allowed. The systemthen removes fluid at the maximum rate that automatically maintains thedesired CVP. That is, the system of present invention automaticallybalances the fluid removal rate with the fluid flow rate from theinterstitial spaces into the blood.

It should be appreciated that normal CVP levels is between 2 and 6 mmHg. Elevated CVP is indicative of over-hydration, while decreased CVPindicates hypovolemia. Using the present invention, a patient may beginan ultrafiltration session with a CVP above normal, e.g. 7-8 mm Hg, andend the session at a final CVP target of 3 mm Hg through, for example, a6 hour treatment session. However, if midway through the treatmentsession, CVP has fallen more than 50% of the desired drop, while thefluid removed has only reached 50% of the final target for removal, thesystem can be reprogrammed to reduce the goal for fluid removal orreduce the rate of fluid removal. Other actions can be taken based onmore complicated algorithms. The net result is that hypovolemia isavoided by monitoring the rate and actual value of CVP. It should beappreciated that this approach may also be useful in controlling fluidremoval rates not only during hemofiltration, but for all types of renalreplacement therapies.

Monitoring and Maintaining Volumetric Accuracy

Embodiments of the dialysis system disclosed herein further incorporatemethods and systems for maintaining volumetric accuracy of replacementfluid and output fluid in a hemodialysis system. In one embodiment, themethod involves swapping pumps used at the replacement fluid side and onthe output side such that an equal quantity of fluid is pumped at eachside. The pump-swapping system of the present invention provides anaccurate means for maintaining the fluid volumes during the dialysisprocedure, and can be inexpensively implemented, for reusable as well asdisposable devices.

FIG. 65 illustrates an exemplary pump swapping circuit as employed inone embodiment. A pump swapping circuit 6500 for hemofiltrationcomprises two pumps, Pump A 6545 and Pump B 6555. These two pumps are influid communication with the replacement fluid circuit R 6560 and theoutput fluid circuit O 6570. The fluid communication is facilitated bymeans of two pairs of two-way valves 6505 and 6507. For the replacementfluid circuit R 6560, a replacement fluid source 6510 provides fluidthrough a restrictor 6517 to the pair of two-way valves 6505.Thereafter, depending on which of the two valves in the pair 6505 isopen, the replacement fluid is pumped by either Pump A 6545 or Pump B6555 to the second set of two-way valves 6507. This set of two-wayvalves 6507 channelizes the replacement fluid to the replacement circuitR 6560, which is in fluid communication with the output 6542 of thedialyzer 6540. In the present embodiment, the communication with theoutput 6542 of the dialyzer 6540 is a post-dialyzer infusionconfiguration. In another configuration known in the art, thecommunication is with the input 6544 of the dialyzer instead. One ofordinary skill in the art would appreciate that either configuration maybe used, without impacting the scope of the invention.

The pair of two-way valves 6505 can be configured to alternatively opensuch that any of the following fluid communication paths may beestablished:

-   -   Between output fluid circuit O 6570 and Pump A 6545;    -   Between replacement fluid circuit R 6560 and Pump B 6555;    -   Between replacement fluid circuit R 6560 and Pump A 6545; and,    -   Between output fluid circuit O 6570 and Pump B 6555.

The system 6500 also comprises two pressure sensors 6515 and 6516. Thesensor 6516 is located on the output circuit O 6570 while the sensor6515 is located proximate to the replacement fluid source 6510. Thepressure sensors 6515 and 6516 are used for monitoring pressure. Thepressure data from these sensors is provided to the active restrictor6517 via a differential amplifier 6525. Depending on the pressuremeasurements, the restrictor 6517 variably restricts the flow ofreplacement fluid as required.

During dialysis, additional fluid may be removed from the patient, ifrequired, in the form of ultrafiltrate (UF). For this purpose, a UF pump6535 is provided that pumps the UF to a bag or drain 6530. Since UFfluid is removed prior to the point of pressure measurement in theoutput fluid sub-circuit O 6570, volumetric accuracy is maintainedirrespective of how much or how little UF is removed.

Operationally, volumetric accuracy in the hemodialysis system of thepresent invention is achieved by swapping the pumps 6545 and 6555 usedon the replacement fluid side and on the output side so that samequantity of fluid is pumped at each point after an even number of swaps.The two pairs of two-way valves 6505 and 6507 facilitate the use of eachof the pumps alternatively with the replacement fluid circuit R 6560 andthe output fluid circuit O 6570.

In one embodiment, the pumps used are peristaltic pumps. One of ordinaryskill in the art would appreciate that other types of pumps may also beused, since volumetric balance in renal dialysis is achieved by the useof a pump-swapping technique, and is not dependent on the type of pump.In one embodiment, Pump A 6545 delivers more fluid per unit time thanpump B 6555. Therefore, this would result in more replacement fluidbeing pumped than output fluid in any given period of time.

One of ordinary skill in the art would appreciate that pumps thatinclude a disposable element can have a pumping rate differential sincevolumes across disposable elements are not equal, even if they are ofthe same size and type. For example, the volumes of two disposablesyringes of nominally the same size inserted within two syringe-pumpassemblies will not be exactly the same. One of ordinary skill in theart would also appreciate that two pumps that do not have disposableelements can usually be tuned so there will be no differential inpumping rate between the two. Examples of pumps using disposableelements that can be implemented with the present invention include, butare not limited to, rotary or linear peristaltic pumps, syringe pumps,rotary vane pumps, centrifugal pumps, and diaphragm pumps.

To achieve volumetric balance between the replacement fluid and outputfluid, the pumps 6545 and 6555 are swapped every T minutes. At the endof the first ‘T’ minute interval, owing to the pumps' specificcharacteristics, pump A 6545 would deliver more volume than pump B 6555.The fluid volume delivered by pump A 6545 is termed as ‘Q’. Thus, ifduring the first pumping interval ‘T’, replacement fluid is routedthrough Pump A 6545 and output fluid is routed through Pump B 6555, thenat the end of time interval T, ‘Q’ more replacement fluid would havebeen pumped in the replacement fluid circuit R 6560 than output fluid inthe circuit O 6570.

Thereafter, pumps A 6545 and B 6555 are swapped in the next timeinterval and output fluid in circuit O 6570 is pumped by Pump A 6545 andreplacement fluid in circuit R 6560 is pumped by pump B 6555. In thisinterval, ‘Q’ less replacement fluid in R 6560 will be pumped thanoutput fluid in O 6570. Therefore, at end of the second interval (and atthe end of an even number of swaps), the difference in volume pumpedduring each interval would be: Q−Q=0. Thus, the net volume difference iszero after an even number of swaps, thereby achieving volumetric balancebetween the replacement fluid infused and the output fluid coming backfrom the patient through the dialyzer. One of ordinary skill in the artwould appreciate that there may be a minute change in the flow ratethrough a pump over time, and consequently, in the volume delivered perunit time. In that case, the net volume difference may not be exactlyzero, but very close to zero.

The volume pumped by a peristaltic pump depends on head pressure. Headpressure for the pumps is a function of the sub-circuit, not the pump,and is systematically different in the replacement fluid circuit R 6560versus the output circuit O 6570. It is thus necessary to equalize headpressures experienced by Pump A 6545 and Pump B 6555.

In one embodiment, head pressures are equalized by modulating therestrictor 6517 on the input circuit from the replacement fluid source6510. The restrictor modulation is achieved based on the output of adifferential amplifier 6525, which calculates pressure differentialsbetween the pressure values measured by head pressure sensors 6515 and6516 located between the pumps 6545 and 6555. The amount of compensationrequired will depend on how much a pump is influenced by head pressuresin the replacement fluid circuit R 6560 and the output fluid circuit O6570. The head pressure in circuit O 6570 will typically be negative.The head pressure in circuit R 6560 will be positive if the replacementfluid bags (source) 6510 are elevated above the level of the pumps andnegative if the bags are vertically positioned below the level of thepumps. For pumps utilizing heavy duty pump tube segments, thedifferences may be relatively small.

As mentioned, head pressures are equalized by measuring the pressures inthe sub-circuits R 6560 and O 6570, providing those pressures as inputto a differential amplifier 6525, and modulating the inflow from thereplacement fluid bag 6510 with a variable restrictor 6517 insub-circuit R 6560 that is regulated by the output of the differentialamplifier 6525. Since the head pressure is a function of the sub-circuitrather than the pump, therefore, it is necessary to regulate the averagedifference between the head pressures of the two sub-circuits in anunregulated state. The pressures in the unregulated state can bemeasured initially and at desired intervals during operation by brieflyturning off regulation. This recalibration does not require stoppingpumping.

In one embodiment, pump head pressures can vary from zero to overseveral hundred mm Hg, depending on the dialyzer incorporated, theheight of the replacement fluid relative to the dialysis machine and thedialysate flow rate setting. For example, for a dialysate flow of 200ml/min and replacement fluid bags hung 5-10 inches above the dialysismachine, the pressure differentials are in the range of 10 mm Hg. Ingeneral, when the pressure in replacement circuit R 6560 is higher thanthe pressure in circuit O 6570, the flow restrictor 6517 will restrictflow from the replacement fluid source 6510 in order to compensate forthe pressure differential.

For a dialysis system that uses a closed-loop dialysate circuit wherethe dialysate fluid is being constantly recycled passing through asorbent cartridge, FIG. 66 presents an alternative pump swappingcircuit. The pump swapping circuit 6600 for hemofiltration comprises twopumps, Pump A 6645 and Pump B 6655. These two pumps are in fluidcommunication with the return fluid circuit R 6660 and the sorbent fluidcircuit S 6670. The fluid communication is facilitated by means of twopairs of two-way valves 6605 and 6607. For the return fluid circuit R6660, a reservoir fluid source 6610 provides fluid through a restrictor6617 to the pair of two-way valves 6605. Thereafter, depending on whichof the two valves in the pair 6605 is open, the replacement fluid ispumped by either Pump A 6645 or Pump B 6655 to the second set of two-wayvalves 6607. This set of two-way valves 6607 channelizes fluid through asorbent cartridge 6608 and through the reservoir 6610 to the returncircuit R 6660, which is in fluid communication with the input port 6642of the dialyzer 6640.

The pair of two-way valves 6605 can be configured to alternatively opensuch that any of the following fluid communication paths may beestablished:

-   -   Between sorbent fluid circuit S 6670 and Pump A 6645;    -   Between return fluid circuit R 6660 and Pump B 6655;    -   Between return fluid circuit R 6660 and Pump A 6645; and,    -   Between sorbent fluid circuit S 6670 and Pump B 6655.

The system 6600 also comprises two pressure sensors 6615 and 6616. Thesensor 6616 is located on the sorbent circuit S 6670 while the sensor6615 is located proximate to the reservoir fluid source 6610. Thepressure sensors 6615 and 6616 are used for monitoring pressure.Pressure data from these sensors is provided to the active restrictor6617 via a differential amplifier 6625. Depending on the pressuremeasurements, the restrictor 6617 variably restricts the flow ofreservoir fluid as required.

As in the previous embodiment, this embodiment has a provision for a UF(ultrafiltrate) pump 6635, so that additional fluid in the form of (UF)may be removed from the patient during dialysis, if required. The UFpump 6635 pumps the ultrafiltrate to a bag or drain 6630. Since UF fluidis removed prior to the point of pressure measurement in the sorbentfluid sub-circuit S 6670, volumetric accuracy is maintained irrespectiveof how much or how little UF is removed.

Operationally, volumetric accuracy in the hemodialysis system of thepresent invention is achieved by swapping the pumps 6645 and 6655 usedon the return fluid side and on the sorbent side so that the samequantity of fluid is pumped at each point after an even number of swaps.The two pairs of two-way valves 6605 and 6607 facilitate the use of eachof the pumps alternatively with the return fluid circuit R 6660 and thesorbent fluid circuit S 6670.

In one embodiment, the pumps used are peristaltic pumps. One of ordinaryskill in the art would appreciate that other types of pumps may also beused, since volumetric balance in renal dialysis is achieved by the useof a pump-swapping technique, and is not dependent on the type of pump.In one embodiment, Pump A 6645 delivers more fluid per unit time thanpump B 6655. Therefore, this would result in more return fluid beingpumped than sorbent fluid in any given period of time.

One of ordinary skill in the art would appreciate that pumps thatinclude a disposable element can have a pumping rate differential sincevolumes across disposable elements are not equal, even if they are ofthe same size and type. One of ordinary skill in the art would alsoappreciate that two pumps that do not have disposable elements canusually be tuned so there will be no differential in pumping ratebetween the two.

To achieve volumetric balance between the return fluid and sorbentfluid, the pumps 6645 and 6655 are swapped every T minutes. At the endof the first ‘T’ minute interval, owing to the pumps' specificcharacteristics, pump A 6645 would deliver more volume than pump B 6655.The fluid volume delivered by pump A 6645 is termed as ‘Q’. Thus, ifduring the first pumping interval ‘T’, reservoir fluid is routed throughPump A 6645 and sorbent fluid is routed through Pump B 6655, then at theend of time interval T, ‘Q’ more reservoir fluid would have been pumpedin the return fluid circuit R 6660 than sorbent fluid in the circuit S6670. Thereafter, pumps A 6645 and B 6655 are swapped in the next timeinterval and sorbent fluid in circuit S 6670 is pumped by Pump A 6645and return fluid in circuit R 6660 is pumped by pump B 6655. In thisinterval, ‘Q’ less reservoir fluid in R 6660 will be pumped than sorbentfluid in S 6670. Therefore, at end of the second interval (and at theend of an even number of swaps), the difference in volume pumped duringeach interval would be: Q−Q=0. Thus, the net volume difference is zeroafter an even number of swaps, thereby achieving volumetric balancebetween the return fluid infused and the sorbent fluid coming back fromthe patient through the dialyzer. Again, since there may be some,usually small, change in the flow rate through a pump over time, so thatthe volume delivered per unit time changes, the net volume differencemay not be exactly zero at times, but substantially close to zero.

As is true for the embodiment shown in FIG. 65, the volume pumped by aperistaltic pump in the embodiment illustrated in FIG. 66 depends onhead pressure. Further, since head pressure for the pumps is a functionof the sub-circuit, not the pump, and is systematically different in thereturn fluid circuit R 6660 versus the sorbent circuit S 6670, it isnecessary to equalize head pressures experienced by Pump A 6645 and PumpB 6655.

In one embodiment, head pressures are equalized by modulating therestrictor 6617 on the input circuit from the reservoir fluid source6610. The restrictor modulation is achieved in a similar manner as withthe embodiment of FIG. 65, and is based on the output of a differentialamplifier 6625. The differential amplifier 6625 calculates pressuredifferentials between the pressure values measured by head pressuresensors 6615 and 6616 located between the pumps 6645 and 6655. Theamount of compensation required will depend on how much a pump isinfluenced by head pressures in the return fluid circuit R 6660 and thesorbent fluid circuit S 6670. The head pressure in circuit S 6670 willtypically be negative. The head pressure in circuit R 6660 will bepositive if the reservoir 6610 is elevated above the level of the pumpsand negative if the reservoir is vertically positioned below the levelof the pumps. For pumps utilizing heavy duty pump tube segments, thedifferences may be relatively small.

As mentioned, head pressures are equalized by measuring the pressures inthe sub-circuits R 6660 and S 6670, providing those pressures as inputto a differential amplifier 6625, and modulating the inflow from thereservoir 6610 with a variable restrictor 6617 in sub-circuit R 6660that is regulated by the output of the differential amplifier 6625.Since the head pressure is a function of the sub-circuit rather than thepump, therefore, it is necessary to regulate the average differencebetween the head pressures of the two sub-circuits in an unregulatedstate. The pressures in the unregulated state can be measured initiallyand at desired intervals during operation by briefly turning offregulation. This recalibration does not require stopping pumping.

In one embodiment, pump head pressures may vary from zero to overseveral hundred mm Hg, depending on the dialyzer incorporated, theheight of the reservoir relative to the dialysis machine and thedialysate flow rate setting. For example, pressure differentials are inthe range of 10 mm Hg for a dialysate flow of 200 ml/min. and with thereservoir located 5-10 inches above the pumps of the dialysis machine.When pressure in circuit R (return) 6660 is higher than pressure incircuit S 6670 (from dialyzer), the flow restrictor 6617 restricts flowfrom the reservoir 6610 to compensate.

In either the configuration in FIG. 65 or the one in FIG. 66, at timesthere may be increased outflow into the dialysate circuit segment (O6570 or S 6670, respectively), due to increased dialyzer trans-membranepressure (TMP). This may happen, for example, because of an outflowobstruction of the dialyzer (6540 or 6640, respectively). In such acase, there may be the possibility of the restrictor (6517 or 6617,respectively) not being able to open up sufficiently to regulate, forexample, if the replacement fluid source 6510 or reservoir 6610 islocated below the level of the pumps. To counter this, a booster pumpmay be inserted in the circuit after the replacement fluid source 6510or the reservoir 6610. The booster pump may be configured to be turnedon automatically in case the differential amplifier (6525 or 6625,respectively) and/or the restrictor (6517 or 6617, respectively) isunable to regulate the system.

Since a time gap is created during a pump swap, it is necessary tocalculate the time interval between swaps. This calculation is afunction of the maximum allowable difference in the amount of fluidpumped, as determined by two functions, at any given time. Thecalculation must compensate, however, for differences in head pressurepresented to the pumps for fluid coming from the replacement-fluidcontainers and that coming back from the patient through the dialyzer.

The frequency at which the pumps are swapped depends on the maximumacceptable increase or decrease in fluid volume in a patient during thedialysis process for any given interval T. For example, if the allowablenet gain or loss is 200 ml and the replacement fluid is being input at arate of 200 ml/min, then the pump swapping frequency for various levelsof differences in the pumping rate of the two pumps are detailed in atable 6700 in FIG. 67.

The following description refers to the components in the embodimentshown in FIG. 65, but is also applicable in the same manner to theembodiment illustrated in FIG. 66. Referring to FIG. 67, the first row6701 of the table illustrates that when the percentage difference in thepumping rates of the two pumps—pump A 6545 and pump B 6555—is 1%, whichamounts to a fluid volume difference of 2 ml (for an allowable net gainor loss of 200 ml), then swapping the pumps at a time interval of 200ml/2 ml=100 minutes would achieve zero volumetric difference. Similarly,for a pumping rate difference of 2%, swapping the pumps at an intervalof 200 ml/4 ml=50 minutes would achieve volumetric balance, and so on.This is illustrated in the subsequent rows of table 6700.

Even if a much more stringent limit was to be put on the maximum volumeof fluid that can be infused into or removed from a patient, such as ±30ml as opposed to ±200 ml in the above example, the swap interval for thecase when the pumping difference is 5% would be 30 ml/10 ml=3 minutes.Since only switching the two-way valves (shown as 6505 in FIG. 65) isneeded for swapping the pumps and starting and stopping the pumps is notrequired, even a short interval of 3 minutes (or shorter) is practicallyimplementable.

Swapping the pumps more frequently can also mitigate any divergence inpump tube performance. Since in the system of the present invention, thetubes of both pumps are subject to the same number of impacts, theperformance of the pumps tends not to diverge.

When using the pump-swapping approach, if the process does not stop atan even number of swaps it could result in a differential error in thevolumetric balance of the replacement fluid and the output fluid.Therefore, in one embodiment, the system is configured to stop only whenan even number of swaps are completed, unless the system is overridden.The potential impact of the problem ending in a net differential errorcan also be reduced by swapping the pumps more frequently. In any case,it can be guaranteed that any net difference will not be outside theoriginally set boundary for maximum allowable net fluid loss or gain,such as ±200 ml. Therefore, in one embodiment, the present inventioncomprises a controller in data communication with all operative pumps.The controller comprises software with a counter that tracks, byincrement, the number of pump swaps. Where the number of pump swaps isuneven, the controller implements a blocking signal which prevents thesystem from being shut down. The controller releases the blocking signalwhen the counter is an even number, thereby permitting a shutdown of thesystem. The controller is further responsible for transmitting theswapping signal which causes the appropriate valves to open and close,thereby effectuating the pump swap.

During the process of pump swapping, there will be a small amount ofresidual fluid that will shift from one sub-circuit to the other. Forexample, if the peristaltic pump tubing is 0.8 ml/inch and the pump-tubesegment length is 3 inches, the residual would be 2.4 ml (3 inch×0.8ml/in =2.4 ml) per each time period. In an exemplary time period of 50minutes, and with a pumping rate of 200 ml/min, 10 liters of fluid (50min×200 ml/min=10,000 ml) will be pumped. Therefore, the percentage ofresidual to the total fluid pumped in liters is only 0.024% (2.4ml/10,000 ml=0.024%). The effect of even this small percentage ofresidual will be nullified because a shift between the sub-circuitsoccurs due to pump swapping, which cancels out the net effect.

With regards to the issue of residual fluid from one sub-circuit cominginto the other, the fluid coming out of the dialyzer comes from thepatient only, and therefore, it is perfectly safe to put that fluid backinto the patient along with the sterile replacement fluid.

As mentioned previously, during dialysis, additional fluid may beremoved from the patient if required, in the form of ultrafiltrate (UF),and a UF pump is provided for this purpose in the system of presentinvention. Further, volumetric accuracy is maintained irrespective ofhow much or how little UF is removed.

When pumping out ultrafiltrate to remove excess fluid from the patient,if the system has a lower pump rate, such as of the order of 10 ml/min,as opposed to a high rate such as 200 ml/min, achieving a definedoverall volumetric accuracy is easier. For example if the accuracyrequired is ±30 ml, then over a time period of 60 minutes, 600 ml willbe pumped with a pump rate of 10 ml/min. This implies that thepercentage accuracy achieved is 30 ml/600 ml=0.05 or 5%, which isreasonable to obtain. One of ordinary skill in the art would, however,appreciate that the system of the present invention is capable ofachieving the desired volumetric accuracy regardless of the pump rate ofthe UF pump in the dialysis device.

Disposable Conductivity Sensor

FIG. 86 depicts, among other elements, a disposable conductivity sensor8690 comprising a tubular section with a first end for receiving a firstdisposable tubing segment and a second end for receiving a seconddisposable tubing segment. The tubular section comprises a firstplurality of probes that extend into the interior volume defined by thetubular section and constitute the fluid flow path. In one embodiment,at least three separate, elongated probes are employed. In anotherembodiment, at least four separate, elongated probes are employed.

The disposable conductivity sensor 8690 is adapted to attach to acomplementary, mating second plurality of probes that are fixedly and/orpermanently attached to the exterior side of the control unit.Preferably, the site of attachment comprises a portion of the exteriorsurface of the control unit proximate to, or on the same side as, thedialyzer, as previously described in relation to FIG. 1. Operationally,disposable conductivity sensor 8690 is snapped into a temporary, butattached, relation to the complementary, mating non-disposable pluralityof probes. Therefore, the second plurality of probes is received into,and positioned in communication with, the first plurality of probes. Theprobes then operate by emitting and detecting signals within the fluidflow path defined by the first disposable tubing segment, tubularsection of the conductivity sensor, and second disposable tubingsegment, as previously discussed herein and then transmitting detectedsignals to a memory and processor within the control unit for use inmonitoring and controlling the dialysis system.

Valve Systems

To allow a control flow through the blood and dialysate circuits and toselect the desired mode of operation (hemodialysis or hemofiltration),in one embodiment the system is provided with two-way valve(s), asdescribed above. These valves can be actuated by a user to directdialysate flow either through the dialyzer in one mode of operation orto deliver infusate grade dialysate flow directly to a patient, in asecond mode of operation. These two-way valves can also be integratedwith the compact manifold of the dialysis circuit. This is illustratedin FIG. 68. It should be noted that in FIGS. 68 through 70, for thepurpose of clarity, corresponding elements have the same numbers.

Referring to FIG. 68, the extracorporeal blood processing system 6800comprises a plastic molded compact manifold 6810 that encapsulates aplurality of molded blood and dialysate fluidic paths as well as aplurality of sensor areas, valves and fluidic pump segments. Thedialyzer 6805 when connected to the arterial blood tube 6801 and venousblood tube 6802 of manifold 6810 completes the blood circuit of system6800. In one embodiment, the dialyzer 6805 is disposable. Two lines,6803 and 6804, are used for circulating spent and fresh dialysaterespectively. For operating the system 6800 in either of the two modes(hemodialysis and hemofiltration), a two-way valve 6845 and a backuptwo-way valve 6846 are provided.

Back up valve 6846 is employed because the dialysate used inhemodialysis is not sterile and not infusion grade while the fluid usedin hemofiltration is. If operating in hemodialysis mode or if there is aleak or other failure of valve 6845, valve 6846 provides doubleprotection against that fluid being pumped into the patient bloodstream. Inclusion of backup valve 6846 allows the use of one manifoldfor both hemodialysis and hemofiltration safely. As noted above, two wayvalves such as backup valve 6846 are composed of two single valves. Inthis case both one way valves are in series and so by closing both portsof two way valve 6846 double protection is afforded preventing dialysatefrom entering the blood stream. In an alternate embodiment, a manifoldcan be made that is only intended for hemodialysis, having no connectionbetween dialysis fluid circuit and blood circuit, thereby permittingvalve 6846 to be safely eliminated.

FIG. 69A illustrates in further detail the circuit for ahemodialysis/hemofiltration system according to one embodiment of thepresent invention. Spent dialysate and fresh dialysate tubes 6903 and6904 respectively are connected to a dialysate regeneration system 6906,thereby completing the dialysate circuit of the system 6900. Thedialysate regeneration system 6906 further comprises disposable sorbentcartridges 6915 and a reservoir 6934 to hold dialysate cleansed bycartridges 6915. Other components of the system shown in FIG. 69A areexplained with reference to FIG. 69B, which shows an exploded view ofthe extracorporeal blood processing system 6900 configured to operate inhemodialysis mode. Corresponding elements in FIGS. 69A, 69B, and 69Chave the same numbers.

Blood circuit 6920 comprises a peristaltic blood pump 6921 that draws apatient's arterial impure blood along the tube 6901 and pumps the bloodthrough dialyzer 6905. A syringe device 6907 injects an anticoagulant,such as heparin, into the drawn impure blood stream. Pressure sensor6908 is placed at the inlet of the blood pump 6921 while pressuresensors 6909 and 6911 are placed upstream and downstream of the dialyzer6905 to monitor pressure at these vantage points.

As purified blood flows downstream from the dialyzer 6905 and back tothe patient, a blood temperature sensor 6912 is provided in the line tokeep track of temperature of the purified blood. An air eliminator 6913is also provided to remove accumulated gas bubbles in the clean bloodfrom the dialyzer. A pair of air (bubble) sensors (or optionally asingle sensor) 6914 and a pinch valve 6916 are employed in the circuitto prevent accumulated gas from being returned to the patient.

The dialysate circuit 6925 comprises two dual-channel pulsatiledialysate pumps 6926, 6927. Dialysate pumps 6926, 6927 draw spentdialysate solution from the dialyzer 6905 and the regenerated dialysatesolution from reservoir 6934 respectively. At the point where useddialysate fluid from the dialyzer 6905 enters the dialysate circuit6925, a blood leak sensor 6928 is provided to sense and prevent anyleakage of blood into the dialysate circuit. Spent dialysate from theoutlet of the dialyzer 6905 then passes through the bypass valve 6929 toreach two-way valve 6930. A pressure sensor 6931 is placed between thevalves 6929 and 6930. An ultrafiltrate pump 6932 is provided in thedialysate circuit, which is operated periodically to draw ultrafiltratewaste from the spent dialysate and store it in an ultrafiltrate bag6933, which is emptied periodically.

As mentioned previously, spent dialysate is regenerated using sorbentcartridges. The dialysate regenerated by means of sorbent cartridge 6915is collected in a reservoir 6934. The reservoir 6934 includesconductivity and ammonia sensors 6961 and 6962 respectively. From thereservoir 6934, regenerated dialysate passes through flow restrictor6935 and pressure sensor 6936 to reach a two-way valve 6937. Dependingupon patient requirement, desired quantities of infusate solution fromthe reservoir 6950 and/or concentrate solution from the reservoir 6951may be added to the dialysis fluid. Infusate and concentrate are sterilesolutions containing minerals and/or glucose that help maintain mineralslike potassium and calcium in the dialysate fluid at levels prescribedby the physician. A bypass valve 6941 and a peristaltic pump 6942 areprovided to select the desired amount of infusate and/or concentratesolution and to ensure proper flow of the solution into the cleanseddialysate emanating from the reservoir 6934.

The dialysate circuit comprises two two-way valves 6930 and 6937. Thevalve 6930 directs one stream of spent dialysate to a first channel ofdialysate pump 6926 and another stream of spent dialysate to a firstchannel of dialysate pump 6927. Similarly, valve 6937 directs one streamof regenerated dialysate to a second channel of dialysate pump 6926 andanother stream of regenerated dialysate to a second channel of dialysatepump 6927.

Streams of spent dialysate from pumps 6926 and 6927 are collected bytwo-way valve 6938 while streams of regenerated dialysate from pumps6926 and 6927 are collected by two-way valve 6939. The valve 6938combines the two streams of spent dialysate into a single stream that ispumped via pressure sensor 6940 and through sorbent cartridges 6915where the spent dialysate is cleansed and filtered, then collected inthe reservoir 6934. The valve 6939 combines the two streams ofregenerated dialysate into a single stream, which flows to the two-wayvalve 6945 through a bypass valve 6947. A pressure sensor 6943 and adialysate temperature sensor 6944 are provided on the dialysate flowstream to the two-way valve 6945.

By reversing the state of two way valves 6930, 6937, 6938 and 6939 thetwo pumps 6926 and 6927 are reversed in their action of one withdrawingdialysis fluid from the dialyzer 6905 and the other supplying dialysisfluid to the dialyzer 6905. Such reversal, when done periodically overshort periods of time relative to the dialysis session, insures thatover the longer period of the entire dialysis session the dialysatefluid volume pumped into the dialyzer equals the amount of fluid pumpedout and the only total fluid volume lost by dialysis circuit 6925 isthat removed by ultrafiltrate pump 6932, as discussed above.

In hemodialysis mode, two-way valve 6945 allows the regenerateddialysate to enter dialyzer 6905 to enable normal hemodialysis of thepatient's blood. One side of valve 6945 is closed leading to thepatient's blood return line. Another two-way valve 6946 acts as abackup, keeping dialysate form the patient's blood line with both portsof valve 6946 closed even if valve 6945 leaks or fails.

Referring to FIG. 69C, in hemofiltration mode, the two-way valve 6945can be actuated to direct a stream of fresh ultrapure dialysate fromreservoir 6952 through valve 6946, now with both ports open to directlyenter the stream of purified blood emanating from the dialyzer andflowing back to the patient.

It should be noted by persons of ordinary skill in the art that thebackup two-way valve 6946 is a redundant safety valve to ensure that inhemodialysis mode failure of one valve 6945 does not result in infusionof regenerated dialysate directly into the patient. That is, both thevalves 6945 and 6946 are capable of being actuated by the system toallow fluid to be directed to the patient's venous blood line as asafety consideration. In one embodiment the two-way back-up valve 6946is a single valve to allow or stop fluid flow.

It should be further noted by persons of ordinary skill in the art thatvalves as described in the description above are termed as ‘bypass’ or‘two-way’ depending upon their use. Thus, valves are termed ‘bypassvalves’ when they bypass a component, such as the dialyzer. Otherwisethey are termed ‘two-way valves’ and simply direct the flow in at leasttwo directions. However, the bypass and two-way valves may be identicalin construction.

In one embodiment, the two-way valves used in the present invention arefabricated as elastomeric membranes that are pressed against an orificeby a mechanism contained inside the dialysis machine to stop flow havingfluid contact with the rest of the fluidic circuit, as further discussedbelow.

Two-way valves 6945 and 6946 can be used for changing the mode ofoperation for the blood processing system. Referring to FIG. 69C, fluidflow in blood and dialysate circuits 6920 and 6925 is depicted. Sincethe system is operating in hemofiltration mode, the spent dialysate tube6903 is connected to a drain while the fresh, dialysate tube 6904 isconnected to fresh ultrapure and injectable grade dialysate reservoirs6952. Fresh dialysate through a ball-valve drip chamber 6953 passesthrough a heater bag 6954 to flow into the fresh dialysate tube 6904.The rest of the elements and fluidic paths of the blood and dialysatecircuits 6920, 6925 are similar to those of FIG. 69B, except that inhemofiltration fresh dialysate or replacement fluid is introduced intothe dialysate circuit 6925 as the spent dialysate is drained and notreused. Also, in the infusate subsystem, components 6942, 6950, 6941 and6951 are unused.

The blood circuit 6920 comprises a peristaltic blood pump 6921 thatdraws a patient's arterial impure blood along tube 6901 and pumps theblood through dialyzer 6905. An optional pump 6907 injects ananticoagulant, such as heparin, into the drawn impure blood stream.Pressure sensor 6908 is placed at the inlet of the blood pump 6921 whilepressure sensors 6909 and 6911 are placed upstream and downstream of thedialyzer 6905. Purified blood from the dialyzer 6905 is pumped throughtube 6902 past a blood temperature sensor 6912, air eliminator 6913 andair (bubble) sensors 6914 and back to a vein of the patient. A pinchvalve 6916 is also placed to completely stop blood flow if air is sensedby the bubble sensor 6914 in the line upstream of the pinch valve 6916,thereby preventing the air from reaching the patient.

The dialysate circuit 6925 comprises two dual-channel dialysate pumps6926, 6927. Dialysate pumps 6926, 6927 draw spent dialysate solutionfrom the dialyzer 6905 and the fresh dialysate solution from reservoirs6952 respectively. Spent dialysate from the outlet of the dialyzer 6905is drawn through blood leak sensor 6928 and bypass valve 6929 to reachtwo-way valve 6930. Pressure sensor 6931 is placed between the valves6929 and 6930. An ultrafiltrate pump 6932 is operated periodically todraw ultrafiltrate waste from the spent dialysate and store it in anultrafiltrate bag 6933 (that is emptied periodically). Fresh dialysatefrom the reservoirs 6952 passes through flow restrictor 6935 andpressure sensor 6936 to reach two-way valve 6937. Persons of ordinaryskill in the art would realize that in this protocol infusate andconcentrate is not needed and elements 6941, 6942, 6950, 6951 associatedwith those functions may not be used.

The heater bag 6954 raises the temperature of the fresh dialysatesufficiently so that the temperature of the ultrafiltered blood goingback to the patient from the dialyzer 6905 or the overall temperature ofthe mixture of ultrafiltered blood from dialyzer 6905 and the freshdialysate infused directly into the purified blood by actuating thevalves 6945, 6946 is equivalent to the body temperature of the patient,thereby preventing any thermal shock.

FIG. 70 shows an alternative embodiment of the fluidic circuits wherethe backup two-way valve 6946 is not used. The blood circuit comprises aperistaltic blood pump that draws a patient's arterial impure bloodalong tube 7001 and pumps the blood through dialyzer 7005. A syringe orpump 7007 injects an anticoagulant, such as heparin, into the drawnimpure blood stream. Pressure sensor 7008 is placed at the inlet of theblood pump while pressure sensors 7009 and 7011 are placed upstream anddownstream of a manifold segment. Purified blood from the dialyzer 7005is pumped through tube 7002 past a blood temperature sensor 7012, aireliminator 7013 and air (bubble) sensor 7014 and back to a vein of thepatient. A pinch valve 7016 is also placed before circuit connection tothe patient to completely stop blood flow if air is sensed by the air(bubble) sensor 7014 in the line upstream of the pinch valve 7016,thereby preventing the air from reaching the patient.

The dialysate circuit 7010 comprises two dialysate pump segments 7026,7027 in pressure communication with pumps. Dialysate pump segments 7026,7027 draw spent dialysate solution from the dialyzer 7005 and theregenerated dialysate solution from reservoir 7034 respectively. Spentdialysate from the outlet of the dialyzer 7005 is drawn through bloodleak sensor 7028 to reach bypass valve 7029. Flow sensor 7020 is one oftwo flow sensors (the other being flow sensor 7046) which determine thevolume of dialysate flowing through the circuit. Valve 7030 is similarin construction to a two-way valve and is used to bypass dialysate pump7026. Valve 7030 is normally closed in the direction of the bypass. Inthe event the dialysate pump 7026 is stopped, valve 7030 is opened todirect flow around pump 7026. Pressure sensor 7031 is placed between theflow sensor 7020 and the valve 7030. During normal flow, the spentdialysate is pumped through pressure sensor 7040, tube 7003, and sorbentcartridges 7015 where the spent dialysate is cleansed and filtered. Thecleansed/filtered dialysate then enters reservoir 7034. An ultrafiltratepump 7032 is operated periodically to draw ultrafiltrate waste from thespent dialysate and store in an ultrafiltrate bag (not shown) that isemptied periodically.

Regenerated dialysate from the reservoir 7034 passes through tube 7004,flow restrictor 7035, dialysate temperature sensor 7044, flow sensor7046 and pressure sensor 7036 to reach two-way valve 7045 through bypassvalve 7041. When the respective flow paths of bypass valves 7029, 7045and 7041 are activated they direct regenerated dialysate to bypass thedialyzer 7005. Infusate and concentrate streams from infusate andconcentrate reservoirs 7050, 7051 are directed by infusate andconcentrate pump segments 7042, 7043 into the cleansed dialysateemanating from the reservoir 7034 via tube 7037 and the spent dialysatedownstream of flow sensor 7020, respectively.

The two-way valve 7045 determines what mode the system is operating in.Thus, in one mode of operation the two-way valve 7045 allows theregenerated dialysate to enter dialyzer via tube 7060 to enable normalhemodialysis of the patient's blood. In another mode of operation, thetwo-way valve 7045 is actuated to direct fluid flow of ultra pureinfusate grade dialysis fluid into the venous blood line and directly topatient. Accordingly, the versatile valves enable the mode of operationto switch between hemofiltration and hemodialysis. For example, inhemofiltration shown in FIG. 69C, infusible grade fluid is routedthrough the three valves directly into the blood stream where valve 6946connects to the post dialyzer. In this mode valve 6945 prevents thedialysate fluid from entering the lower port of the dialyzer. Inhemodialysis, shown in FIG. 69B, valve 6946 is closed and valves 6947and 6945 route dialysate fluid to the dialyzer. It should be noted thatthe embodiment of FIG. 69B uses pump swapping and a plurality of valvesto control fluid volume while the embodiment of FIG. 70 uses flowsensors 7020 and 7046 to control fluid volume.

As discussed above, valves are preferably implemented in a manifoldusing elastic membranes at flow control points which are selectivelyoccluded, as required, by protrusions, pins, or other members extendingfrom the manifold machine. In one embodiment, fluid occlusion is enabledusing a safe, low-energy magnetic valve.

The valve system comprises a magnetic displacement system that islightweight and consumes minimum power, making it ideal even when theportable kidney dialysis system uses a disposable manifold for fluidiccircuits. The system can be used in conjunction with an orifice in anystructure. In particular, an orifice is any hole, opening, void, orpartition in any type of material. This includes pathways in tubing,manifolds, disposable manifolds, channels, and other pathways. One ofordinary skill in the art would appreciate that the presently disclosedvalve system would be implemented with a disposable manifold bypositioning the displacement member and magnets, as further discussedbelow, external to the manifold at the desired valve location. Theactuator is also separate and distinct from the disposable manifold andgenerally part of the non-disposable portion of the kidney dialysissystem.

Functionally, the valve of the present invention has two stable states:open and closed. It operates by using magnetic forces to move adisplacement member against a diaphragm and thereby create sufficientforce to press the diaphragm against a valve seat and cause thediaphragm to close the orifice. Closing of the orifice shuts off fluidflow. The reverse process, namely the use of magnetic forces to move adisplacement member away from the diaphragm and thereby release thediaphragm from compression against the valve seat, opens the orifice andpermits fluid to flow.

It should be appreciated that while the present invention shall bediscussed in terms of a preferred embodiment, depicted in FIGS. 71A and71B, and a non-preferred embodiment, depicted in FIG. 73, the presentinvention is generally directed to any use of a valve in a kidneydialysis system having the following attributes: a) two stable states,open and closed, b) changing states requires energy input, c)maintaining a state does not require energy input, d) a state is changedby the use of magnetic forces to modify the position of a displacementmember which, when modified, causes a valve to either open or close.

In one embodiment, referring to FIGS. 71A and 71B, the valve system ofthe present invention 7100 is used to control fluid flow through afluidic flow channel 7102, which is bounded by valve seats 7104 tothereby create a valve annular orifice 7103. Orifice 7103 is any hole,opening, void, or partition in any type of material, in particular,manifolds, disposable manifolds, channels, and other pathways 7110. Thevalve 7100 is shown in an open state. The components of the valve systeminclude an orifice closing member, a displacement member, a mechanismfor moving the displacement member, an optional optical sensor, a coildriver circuit, and an actuator having a coil.

In one embodiment, the orifice closing member comprises a diaphragm 7106which, when compressed by the displacement member, as discussed below,presses against the valve seats 7104, thereby causing the valve annularorifice 7103 to close. In an open state, the main body of the diaphragm7106 is separated from the valve seats 7104 by a gap 7198. In oneembodiment, the diaphragm 7106 is made from a soft material such assilicone rubber. The diaphragm 7106 must maintain its shape over time,temperature, and actuations. The valve 7100 relies upon the diaphragmmaterial 7106 to return to its uncompressed shape when the displacementmember (compressing force) is removed in the open state.

One of ordinary skill in the art should appreciate that the orificeclosing member can comprise any combination of spring, compressible, ornon-compressible structures which, when pushed by the displacementmember, closes the orifice. In one embodiment, the valve seats 7104 canbe molded into a manifold. Suitable materials for the valve seat arepolycarbonate, ABS and similar plastics. The valve orifice 7103 in thepreferred embodiment ranges from 0.1 to 0.3 inches in diameter (and moreparticularly 0.190 inches). Orifice dimensions can be increased toincrease flow for alternate applications of the invention or,alternatively, decreased to decrease flow for alternate applications.

In one embodiment, the displacement member comprises a plunger cap, orhousing, 7110, which, when the valve is in an open state, is alignedagainst the diaphragm 7106, but not substantially compressing thediaphragm 7106. Positioned inside the plunger cap 7110 is a compliantcomponent, such as a spring 7112 and the head of plunger 7199, which areseparated by an air gap 7114. The plunger cap 7110 is encompassed on theoutside by a fluid seal 7120, which, in one embodiment, is a thin, softsilicone rubber washer. In one embodiment, the plunger cap 7110 isforced against the silicone rubber washer and compresses the washer toform the fluid seal 7120. When in a closed position, the plunger cap7110 is not forced against the washer, which is therefore not compressedand positioned loose to the end cap 7130. The spring 7112 is any elasticor compliant material and, in one embodiment, comprises a wave spring.

The plunger cap 7110, internal spring 7112, air gap 7198, plunger head7199, plunger body 7140, and core 7142 are the components of thepreferred displacement member of the present invention. In oneembodiment, the plunger body 7140 has an outer diameter in the range of0.1 to 0.2 inches (more particularly 0.122 inches) and is approximately0.5 to 2.5 inches long. It should be appreciated that the plunger body7140 is any rod structure of any length, depending on the application.The plunger body 7140 is positioned within an annular core 7142, whichhas one larger end and one smaller end, and is attached to the core viaany method known to ordinary skill in the art, including epoxy, screwattachment, pinned, or welded. The outer diameter of the larger end ofthe core 7142 is in the range of 0.3 inches to 0.5 inches (and moreparticularly 0.395 inches), the thickness is in the range of 0.03 to0.15 inches (and more particularly 0.05 to 0.10 inches), and the lengthis in the range of 0.50 to 1.75 inches long (and more particularly 1.05inches). The small end of the core 7142 has a diameter of 0.1 to 0.4inches, and more particularly 0.25 inches.

At least partially encompassing the small end of the core is a coilbobbin 7195 which keeps the coil 7148 in place and provides dimensionalstability to the coil 7148. A gap preferably exists between the coilbobbin 7195 and core 7142. The size of the gap is approximately 0.01 to0.03 inches (and more particularly 0.02 inches). The coil bobbin 7195is, in one embodiment, a glass filled nylon structure, which should benonmetallic and non-ferromagnetic. The coil bobbin 7195 is an annularstructure with an outer diameter of a size sufficient to provide a tightfit into the housing bore and an inner diameter sufficient to enclosethe core such that it has room to move and undergo some degree ofthermal expansion. The two end caps 7130, 7160 wedge the bobbin 7195into place and keep it from moving or slipping, particularly whenexposed to electromagnetic forces.

The plunger body is made of metal or non-metal material, such as brassor fiberglass, and the core is also made of metal, particularly steel.Preferably, the plunger body is non-magnetic and the core body isferrous-magnetic. As discussed further below, the plunger body 7140 andcore 7142 are moved by the mechanism for moving the displacement member.

The mechanism for moving the displacement member comprises a largemagnet component, a small magnet component and a housing within whichthe magnets and a portion of the displacement member, namely the plungerbody 7140 and core 7142, are contained. More particularly, referring toFIGS. 71A and 71B, the mechanism to moving the displacement membercomprises a large magnet end cap 7130, to hold and align the largemagnet, a large magnet 7132, an elastic material 7134, a gap 7197, acoil 7148, a small magnet component 7162, a small magnet mount and endcap 7160, and an elastic material 7164.

The large magnet end cap 7130 holds and aligns the large magnetcomponent 7132 and coil bobbin 7195 in place within a housing 7170,referred to as the actuator body which has a borehole through which thecomponents described herein are placed. The large magnet component 7132needs to be properly aligned with the core 7142, plunger body 7140, andsmall magnetic component 7162 to ensure the proper movement of thedisplacement member. Both end caps 7130 and 7160 secure the coil bobbin7195 and coil 7148 in position.

Additionally, a mounting plate can be used to capture and hold end cap7130. In one embodiment, the mounting plate is positioned vertically andflush against the side of the end cap and between the end cap and bore.The mounting plate has a hole in it, roughly the same size as thesmaller diameter of the end cap. A clamping mechanism holds the bodyagainst the plate; alternatively the plate can be permanently fixed,using any bonding technique known to persons of ordinary skill in theart. Unlike the prior art, such as U.S. Pat. No. 6,836,201, in apreferred embodiment, the magnets are located inside, not outside, thebore and provide bearings for the plunger, as discussed below.

The large magnet component 7132 is separated from the core 7142 by a gap7197 and elastic material 7134, such as a silicone washer, which, in oneembodiment, has an outer diameter of 0.3 to 0.5 inches (and moreparticularly 0.37 inches), an inner diameter of 0.1 to 0.3 inches (andmore particularly 0.188 inches), a thickness of 0.005 to 0.015 inches(and more particularly 0.01 inches), and a durometer of 35 to 45 (andmore particularly 40). The small magnet component 7162 is separated fromthe core by an elastic material 7164, such as a silicone washer, which,in one embodiment, has an outer diameter of 0.1 to 0.4 inches (and moreparticularly 0.24 inches), an inner diameter of 0.1 to 0.3 inches (andmore particularly 0.188 inches), a thickness of 0.005 to 0.015 inches(and more particularly 0.01 inches), and a durometer of 35 to 45 (andmore particularly 40). The small magnetic component 7162 is held andkept properly aligned within the housing 7170 by a small magnet mountand end cap 7160. The small magnet end cap screws 7172 also serve tocapture and hold in place the small magnet end caps 7160.

Referring to FIG. 71A, the valve system of the present invention furthercomprises a coil driver circuit board 7150, which drives the actuator,comprising coil 7148, and is preferably mounted to the actuator body7170 via small screws, a coil driver connector 7154, and an opticalsensor 7152, which senses the position of the large end of the core7196. Coil 7148 serves to effectuate changes in magnetic fields in orderto cause movement of the core 7142 and plunger body 7140. In oneembodiment, the coil is approximately 0.05 to 1.5 inches long (and moreparticularly 1 inch long), has an outer diameter of 0.35 to 0.55 inches(and more particularly 0.46 inches), and an inner diameter of 0.15 to0.35 inches (and more particularly 0.26 inches), with six layers of wire29 AWG wire.

The various elastic materials used in the displacement member andmechanism for moving the displacement member provide a “soft” stop tothe movement of the rod 7140 when the valve opens or closes. Inparticular, it serves to ensure the movement of the core does not damagethe magnets.

The large magnet component 7132 can be one unitary magnet or, in apreferred embodiment, comprised of a plurality of magnets, such asthree. The small magnet component 7162 can also be unitary or comprisedof a plurality of magnets. In one embodiment, the magnets are made ofpreferably Alnico, Samarium Cobalt, Neodymium, Rare Earth, or Ceramicmagnets. In one embodiment, the large magnet 7132 is a Neodymium ringmagnet with an outer diameter of 0.2 to 0.5 inches (and moreparticularly 0.375 inches), an inner diameter of 0.05 to 0.3 inches (andmore particularly 0.125 inches), and a length of 0.2 to 0.5 inches (andmore particularly 0.375 inches). In one embodiment, the small magnet7162 is made of a Neodymium ring magnet, with an outer diameter of 0.15to 0.4 inches (and more particularly 0.25 inches), an inner diameter of0.05 to 0.3 inches (and more particularly 0.125 inches), and a length of0.15 to 0.4 inches (and more particularly 0.25 inches). The largermagnet 7132 is used closer to the orifice closing member because thesize is necessary to generate sufficient opposition force to the valveseat. Further, the actuation force caused by the actuation coil issubstantially equal even though the magnets are of a different size,thereby enabling a simple coil driver circuit.

In one embodiment, the rod, plunger or other elongated member 7140 usesthe magnets' center holes as a linear bearing. Accordingly, the magnets'center holes should preferably have a bearing surface, such as chrome orany smooth hard surface with minimal friction. A gap is placed betweenthe coil bobbin 7195 and the core 7142 because of thermal expansion ofthe bobbin, bobbin creepage over time, and bobbin, core, and magnettolerances. However, under all operating conditions, the gap should besufficient such that the plunger body 7140 can move freely and not bindin the openings of the magnets and coil. In a preferred embodiment, thegap is approximately 0.01 to 0.06 inches (and more particularly 0.02inches) at room temperature.

When the valve is closed, referring to FIG. 71B, the valve system of thepresent invention 7100 controls fluid flow through a fluidic flowchannel 7102, which is bounded by valve seats 7104, by compressing theorifice closing member, e.g. diaphragm 7106, and thereby obstructingvalve annular orifice 7103. In a closed state, the main body of thediaphragm 7106 is pressed against the valve seats 7104 and, accordingly,substantially eliminates gap 7198 (seen in FIG. 71A).

Once just adjacent to the diaphragm 7106, the displacement member nowcompresses the diaphragm 7106. In particular, plunger cap 7110 has movedto compress the diaphragm 7106. The plunger cap 7110 has moved because achange in magnetic fields causes the core body 7142 to move toward thelarge magnet component 7132. The core body 7142 stops moving when thecore head 7196 passes through the gap 7197 (in FIG. 71A) and stops atthe elastic material 7134 positioned adjacent to the large magnetcomponent 7132. Movement of the core 7142 causes the plunger body 7140,to which the core 7142 is bonded, to move as well. Movement of theplunger body 7140 causes the plunger head 7199 to move within theplunger cap 7110, pass through the gap 7114 (in FIG. 71A), and compressthe spring 7112. After a certain amount of compression, the plunger cap7110 moves and compresses the diaphragm 7106. Movement of the plungercap 7110 creates a new gap 7192 between the cap body 7110 and theelastic material 7120 that is positioned adjacent to the large magnetend cap 7130.

As shown in FIG. 71B, the other components of the valve remain the same,including the actuator body 7170, coil driver circuit 7150, coilconnector 7154, coil 7148, coil bobbin 7193, small end cap screws 7172,optical sensor 7152, and small magnet end cap 7160. It should beappreciated however, that, by virtue of the core 7142 movement, a gap7195 is created between the smaller end of the core 7194 and the elasticmaterial 7164, which is positioned adjacent to the small magneticcomponent 7162.

It should be appreciated that, to close the valve, the displacementmember applies a force to the orifice closing member, e.g. diaphragm7106. The force required, from the displacement member, to deform thediaphragm to the point where the diaphragm touches the valve seat issubstantially linear and can be modeled as a linear spring. However, theforce requirements increase exponentially as the diaphragm is compressedinto the valve seat. Thus, the force profile for the displacement memberbecomes nonlinear and far more complex. Accordingly, there are severalunique challenges associated with the design of the valve and thetolerances between the various components of the displacement member,the orifice closing member, and the hard stop of the displacementmechanism. The displacement mechanism must be able to deliver thenonlinear force profile without permanently deforming the diaphragm.This means that the mechanism must deliver just the right amount offorce.

As discussed above, the displacement member comprises a rod, plunger orother elongated member that is bonded to another structure, referred toas a core, which has a larger diameter and can function as a stopperwhen forced up against another structure, such as a magnet face. One ofordinary skill in the art should appreciate that the displacement memberor moveable member is not limited to a rod and cylinder configuration.On the contrary, it can include non-cylindrical structures, unitarypieces, or multiple pieces that are welded or, in any other manner,bonded together. In sum, the displacement member can comprise manydifferent structures, provided the movement of the member can exert therequisite force on the orifice compressing member in a manner that isreliable and consistent.

For example, referring to FIG. 73, an alternate, less preferredembodiment is shown. For kidney dialysis applications, this embodimentdoes not typically reliably maintain the valve in a closed state. Thedisplacement member 7300 comprises a housing 7305 that includes anelectromagnet 7310 with a substantially cylindrical structure and aborehole 7315 running through it. The electromagnet 7310 is securelypositioned centrally within the housing 7305 by non-magnetic spacers7320 which, in one embodiment are the end caps. The end caps have twopurposes—hold the magnets in place and sandwich the coil in place. Inone embodiment, elements 7331 and 7320 comprise a first unitary pieceand 7305 and 7320 comprise a second unitary piece. A cylindricallyshaped ferromagnetic core 7325, having a first face 7323 and a secondface 7324, is positioned to allow a portion of the core 7325, betweenthe first face 7323 and the second face 7324, to have a linearlyslide-able fit with the bore 7315. The second face 7324 is sufficientlylarger than the bore 7315 thereby restricting the linear motion of thecore 7325. In one embodiment, the second face is differently sizedrelative to the first face to generate sufficient magnetic force to keepthe valve in a closed position. The core 7325 is capable of left andright linear sliding motion within the bore 7315.

Two differently sized magnets 7330, 7335 are also affixed within and atthe two end caps 7331, 7332 of the housing 7305. The first face 7323 ofthe core 7325 contacts with the first magnet 7330 to form a first stablestate of the displacement system 7300 and the second face 7324 of thecore 7325 contacts with the larger magnet 7335 to form a second stablestate of the displacement system 7300. The placement of the permanentmagnets 7330, 7335 is designed to be within the diameter of housing7305, as it reduces the size of the displacement system 7300. A firstrod 7340 connected to the first face 7323 of the core 7325 passesthrough the first magnet 7330 thereby protruding from the housing 7305at one end and a second rod 7345 connected to the second face 7324 ofthe core 7325 passes through the second magnet 7335 thereby protrudingfrom the housing 7305 at the other end. The rods 7340, 7345 can be madeof non-corrosive, non magnetic material known in the art, such as butnot limited to, brass. While one embodiment has two rods connected totwo faces of the core, in an alternate embodiment there is only one rodconnected to one of the faces of the shuttle.

Persons of ordinary skill in the art would appreciate that the magneticforce exerted by the electromagnet 7310 on the core 7325 is sufficientlyhigh to overcome the retention force of the permanent magnets 7330, 7335so that the displacement system 7300 can be changed from the firststable state to the second. Moreover, one of ordinary skill in the artwould appreciate that the rod/plunger 7345 moves with the core 7325,thereby creating the motive force to compress or decompress the orificeclosing member. However, this embodiment has been determined to beinferior to the first embodiment because it fails to sufficiently holdthe closed state.

Several design features of the orifice closing member operating inconjunction with the displacement member and mechanism should beappreciated. First, referring to FIG. 74, and as discussed above inrelation to FIGS. 71A and 71B, a gap 7408 exists between the plunger cap7404 and the orifice closing member 7405, in particular the firstdiaphragm face 7405. The gap 7408 is in the range of 0.040 to 0.070inches and more particularly approximately 0.055 inches. The diaphragmcomprises silicone, preferably of a thickness of 0.040 inches, and canbe modeled as a spring (K_(V2)) having a spring constant of 270 lbf/in.The second diaphragm face 7406 is separated from the valve seat 7407 andacted upon by magnetic forces modeled as a spring, K_(V1) having aspring constant of approximately 22.5 lbf/in and a thickness ofapproximately 0.047 inches.

The rod 7404 translates the force generated by the magnetic attractionof the core 7401 to the magnet 7403 modeled by spring K_(P), which isseparated from the core head 7401 by a washer, e.g. 0.010 inches ofsilicone in a closed state and is separated from core head 7401 byapproximately 0.110 inches in an open state. This silicone washerprovides forces which are modeled as a spring, K_(SL). The core 7401 isbonded to the rod 7404. When the valve is actuated, the rod 7404 movesin the direction of the valve seat 7407 because the core, to which therod is bonded, moves in the direction of the large magnet 7403.

Referring to FIG. 74, K_(V2) and K_(SL) correspond to elastic material,such as silicone, which are modeled as rigid springs. It should beappreciated that, when a valve is in a closed state, there are twopositions of importance. First is the position of the rod against thediaphragm and second is the position of the core face against the largemagnet. When the valve is closed, the rod is pressing on the valvediaphragm with enough force to resist at least 600 mm Hg back pressuregenerated within the fluid passage of the kidney dialysis system. Inthis embodiment, fluid pressures can reach 2600 mm Hg and this system7400 is designed to maintain the diaphragm firmly pressed against thevalve seat to seal the orifice up to and including 2600 mm Hg.

Additionally, when the valve is closed, the core's large face is pulledclose to, or directly against, the large magnet. The magnetic attractionof the core to the large magnet generates the force that the rod appliesto the orifice closing member, e.g. diaphragm. To generate a consistentand reliable force, the spacing between the core face and the face ofthe large magnet must be consistent. Therefore, it is preferred to placean elastic material 7402 between the core face 7401 and the magnet face7404. The elastic material has a nonlinear spring constant and willcompress until the resultant forces for the elastic material equals themagnetic forces. When the rod applies force to the diaphragm via thecore, the core will experience the resultant force. For a staticcondition to occur, the sum of these forces on the core must equal zero.Furthermore, the elastic material serves to protect the magnet face fromchipping or breakage during actuation.

Referring to FIG. 76, when the valve 7600 is in a closed state, the corehead 7605, 7602 has moved away from the small magnet face 7601 (fromposition 7602 a to position 7602). When in position 7602, the core headis separated from the small magnet 7601 by an elastic material 7617,such as a silicone washer having a thickness of approximately 0.015inches. When in position 7605, the core head will have movedapproximately 0.140+/−0.20 inches, including a distance of 0.45+/−0.005inches during which the rod 7608 does not move, and is stopped againstan elastic material 7616 (e.g. a silicone washer having a thickness ofapproximately 0.015 inches), which separates the core head 7605 from thelarge magnet face 7606. The large magnet 7606 is, in turn, separatedfrom the rod head 7607.

When the valve is in an open state, the large magnet 7606 is separatedfrom the rod head 7607 by an elastic material 7615, such as a siliconewasher having a thickness of approximately 0.015 inches. When the valveis in a closed state, the large magnet 7606 is separated from the rodhead 7607 by an elastic material 7615, such as a silicone washer havinga thickness of approximately 0.015 inches and a distance ofapproximately 0.055+/−0.10 inches. When the valve is closed, the rodhead 7607 has moved from being proximate to the large magnet 7606 andelastic material 7615 to being proximate to the valve seat 7610.Specifically, the rod head 7607 moves to compress the diaphragm 7608 andthereby press against an elastic material 7609 (e.g. silicone having athickness of approximately 0.040 inches) which, in turn, presses againstthe valve seat 7610. This causes the valve to close with an approximateforce of 14 N.

It should be appreciated that the configuration of the displacementmember and mechanism relative to the orifice closing member and thetolerances described herein provide for a diaphragm displacement profile7500, as shown in FIG. 75, which is suitable for applications that needto resist at least 600 mm Hg back pressure, such as kidney dialysissystems. Referring to FIG. 75, an exemplary diaphragm displacementprofile 7501 is provided, where the force 7502 exerted by thedisplacement member is provided on the y-axis and the correspondingdiaphragm displacement is provided on the x-axis. The inflection pointon this curve 7503 indicates when the diaphragm starts being compressedagainst the valve seat. To the left of the inflection 7503, thediaphragm is being forced to flex toward the valve seat, but there is nosubstantial compression against the valve seat. To the right of theinflection point 7503, the diaphragm is flexed against the valve seat,deforming the diaphragm material and affecting a good seal against thefluid pressure.

Another important component of the displacement mechanism system is anactuator system 7200 depicted in FIG. 72. During the actuation process,coils 7205 are energized and the magnetic field builds, thus creatingmagnetic force opposing the small magnet attraction force. As the forcebuilds, the core, discussed above, starts to move to the closed position(large magnet). Once the core moves past a point of no return, theattraction forces on the core of the large magnet have overcome theattraction forces of the small magnet. To ensure that the opposingforces caused by the valve diaphragm do not overcome the attractionforces of the large magnet, a gap is provided as discussed above.

The coil design is made of coil form and magnet wire 7210. The size ofthe coil form size is preferably based upon commercially available coilforms, the pulsed current capability of the power supply, and, inparticular, the required actuation force and the power supply voltage.The actuation force is proportional to the amp-turn rating of the coil.In one embodiment, it is preferred to limit the coil current to 6amperes or less.

Factors important in the coil design include the number of layers,packing factor, wire diameter, and coil resistance. In one embodiment,the present invention uses a bobbin with 6 layers of wire andapproximately 0.010 inches space between the bobbin flange diameter andthe last layer. With an insulation requirement of heavy poly nylon and acoil resistance of 3.5+/−0.5 Ohms, the wire size is approximately 29AWG. Any size coil form can be used.

The circuit used to drive the coil is an H-bridge circuit which enablescurrent to be reversed for open and closed operations. The H-Bridgecircuit is driven via a unique pulse width modulated (PWM) signal. ThePWM signal is used to generate a cosine current pulse through the coil.The period of the cosine pulse is related to the mass of the core andthe opposing force. The preferred embodiment does not use a bipolar DCpower switch or sense switch; rather, the optical sensor operates todetermine the position of the core, conclude the valve state, andgenerate an electronic drive cosine waveform to move the plunger in thedesired direction, thereby changing the state of the valve.

Optionally, as shown in FIGS. 71A and 71B as element 7152, the valvesystem 7100 uses a sensor, preferably an optical sensor 7152, todetermine the state of the valve (open or closed). This can be achievedby positioning the optical sensor 7152 in a location that has asufficient difference in reflectivity, or other optical properties,between a valve open state and a valve closed state. For example, whenthe valve is closed, in one embodiment, the large end of the core 7196is positioned against an elastic material 7134 and the large magnetcomponent 7132. The large end of the core 7196 has a width wide enoughto be sensed by a reflective optical sensor 7152, but not too wide sothe optical sensor 7152 has position resolution. The optical sensor 7152will be placed on the outside of the displacement member/mechanism andlook through its body, which is preferably made of transparentpolycarbonate. The optical sensor's 7152 wavelength will be in the nearinfrared range (NIR) so as to have good transmission through thepolycarbonate body. One of ordinary skill in the art would appreciatethat the sensor can be chosen to suit any material structure, providedit includes the appropriate filters. Here, the optical sensor 7152preferably has built into it a long pass optical filter for NIRresponsivity.

Functionally, when the core is in the open position, as shown in FIG.71A, the large end of the core 7196 moves out of the field of view ofthe optical sensor 7152, thus very little reflection will be seen by theoptical sensor. When the large end of the core 7196 is in the field ofview, as shown in FIG. 71B, there will be a reflection that the sensor7152 will see, thus indicating the core is in the closed position. Oneof ordinary skill in the art would appreciate that the sensor 7152 canbe positioned such that it senses a great deal of reflectivity from thecore when the valve 7100 is in the open position and much lessreflectivity (because the core is moved out of the field of view) whenthe valve 7100 is in the closed position. Further, one of ordinary skillin the art would appreciate that the sensor 7152 could be positionedproximate to the gap to sense when the gap is present and when the gapis absent, thereby indicating the state of the valve 7100.

Operationally, as referred to in FIG. 77, a valve is in initially one oftwo states, open or closed. Assuming the valve is in an open state 7701,the first step in closing the valve is to energize the coil drivercircuit 7702 and thereby cause the magnetic field generated by the coilto pass through the core, create an opposing magnetic force between thecore and small magnet, and create a weak attraction force between thelarge magnet and the large end of the core. As the displacement memberstarts to move 7703, the small magnet attraction forces diminish as thelarge magnet attraction forces increase. The displacement member moves7703 until a point of no return, after which the displacement member7704 closes a gap 7704 and compresses the orifice closing member, namelythe diaphragm 7705, against the valve seat 7706. The compression of thediaphragm 7706 causes the diaphragm to close the orifice 7707 and closethe valve 7708.

Assuming the valve is in a closed state 7709, the first step in openingthe valve is to energize the coil driver circuit 7710 and thereby causethe magnetic field generated by the coil to pass through the core,create an opposing magnetic force between the core and large magnet, andcreate a weak attraction force between the small magnet and the smallend of the core. As the displacement member starts to move 7711, thelarge magnet attraction forces diminish as the small magnet attractionforces increase. The displacement member moves 7711 until a point of noreturn, after which the displacement member decompresses the diaphragm7712 away from the valve seat 7713. The orifice opens by virtue of nolonger being covered by the diaphragm 7714. The displacement memberreturns to its original position and recreates the gap 7715, therebyreturning to an open state 7716.

Since the first and second stable states of the core are maintained evenwhen power to the electromagnet is switched off, the displacement systemis able to have low power consumption and low heat generation relativeto prior art actuators where continuous power supply is needed tomaintain states, additionally resulting in high heat generation.

Saline Rinse Back

Referring to FIG. 86, a method and system for safely and efficientlyperforming a saline rinse back is shown. Conventionally, a saline rinseback, which serves to flush the system with saline, is performed bydetaching a tubular segment 8658 that connects the dialysis bloodcircuit to the patient at connection 8651 and attaching the tubularsegment 8658 to a saline source 8602 via connection points 8652 and8653. This conventional approach has disadvantages, however, includingthe breaching of a sterile connection. It should be appreciated that theconnection points can be any form of connection, including luerconnections, snap fits, needleless inserts, valves, or any other form offluidic connection.

Another approach to a saline rinse back includes connecting the salinesource 8602 via connection point 8652 to connection point 8653, whilemaintaining the connection to the patient. While it avoids breaching thesterile connection, it exposes a patient to a saline fluid flow that maycontain air bubbles. Because no air bubble detector is typically presentin the tubular segment 8658 between the point of saline connection 8653and the point of connection to the patient 8651, there is a danger thatan excessively large air bubble would form and, because there is nomechanism to detect such an air bubble and inform the patient, enter thepatient's blood stream, causing substantial injury.

Alternatively, a preferred approach to performing a saline rinse back isto maintain the blood circuit connection between the patient and thedialysis system via tubular segment 8658, which connects to the manifold8600 at port C 8605 and the patient at connection point 8651 andfluidically connect the saline source 8602 to the manifold 8600 at portD 8606. With the patient still fluidically connected to the dialysissystem, saline is permitted to flow, by gravity or applied pressure,into the manifold 8600 via port D 8606, which is adjacent to port C8605. The saline flow serves to flush the manifold 8600 with saline and,in particular, to flow out of the manifold 8600 via port C 8605, throughtubular segment 8658, and into the patient via connection 8651. Becausean air bubble detector is present in region 8654, proximate to port C8605, when the manifold 8600 is installed in the controller unit andtherefore adapted to detect air bubbles in fluid flow exiting port C8605, saline exiting the manifold 8600 and toward the patient will bemonitored for air bubbles, via the air bubble detector in region 8654.If an air bubble is detected, an alarm will sound, thereby signaling toa patient that he or she should either disconnect from the system orextract the air bubble, using a syringe, from access point 8610.Accordingly, this method and system for conducting a saline rinse backmaintains a sterile connection while still monitoring and alarming forthe presence of air bubbles.

Improved Hardware Architecture

Embodiments of the dialysis system disclosed herein may further comprisea hardware architecture that provides for a more rapid method ofterminating system operations. Conventionally, when an alarm state isencountered during dialysis operations or if a user wishes to terminateoperations, an instruction issued at a higher application layer mustprogress through multiple lower layers in order to actively terminatehardware operations. This architecture subjects users to the unnecessaryrisk of a delayed shutdown which, in critical applications, may beunacceptable.

Referring to FIG. 78, the dialysis system comprises at least oneprocessor and a memory for storing programmatic instructions which, whenexecuted, communicates with a software application layer 7805. Thesoftware application layer 7805 interfaces with a master controller 7810that is in data communication with a plurality of field programmablegate arrays responsible for controlling various pumps, sensors, andvalves (Control FPGAs) 7815 and in data communication with a pluralityof field programmable gate arrays responsible for monitoring theoperation of various pumps, sensors, and valves for failure states orstates which exceed accepted operational parameters 7820 (Safety FPGAs).

Control FPGAs 7815 execute hardware instructions for controlling theoperation of all system components, including pumps, sensors, andvalves, and transmitting state information of the components to both thecontroller 7810, which, in turn, processes the information and passescertain data for further processing and/or display to the applicationlayer 7805, and the Safety FPGAs 7820, which monitor the stateinformation for an alarm condition, such as an operational parameterexceeding or not meeting one or more predefined threshold values.

Where the Control FPGAs 7815 generate data indicative of an alarmcondition or generally indicative of a need to terminate or suspendoperations, the controller 7810 or application layer 7805 may issue oneor more commands to terminate operations. Independently, however, theSafety FPGAs 7820 receive the data and may directly issue commands, orotherwise cause, the operation of one or more valves, pumps, or sensorsto terminate, suspend, or otherwise change state. The Safety FPGAs 7820may do so after receiving data directly from the Control FPGAs 7815 orindependently if directly instructed by the controller 7810 or directlyinstructed by the application layer 7805. By having the Safety FPGAsdirectly receive data from the Control FPGAs 7815 and instructions fromthe application layer 7805 and controller 7810, with no mediating layerin between, the system can effectuate a shutdown, suspension, or othermodification in state in response to an alarm condition or userinstructions more rapidly and reliably.

Graphical User Interfaces

Embodiments of the dialysis system further comprise interfaces throughwhich users interact with the system. As previously discussed, thecontroller unit comprises a display for presenting a graphical userinterface to a user. The interface enables a user to accurately measureand verify prescription additives and provides functionality to checkthe integrity and authenticity of the disposables employed in the systemas well as that of the prescription additives.

As previously discussed, the dialysis system comprises a scale, whichcan be integrated on the shelf atop the controller unit, inside thereservoir unit of the portable dialysis system, to the side of thebottom unit proximate holders for the sorbent cartridge or infusate, orin any other location. Measurement readings taken by the digital scaleare displayed via graphical user interfaces (GUIs) shown on the displayintegrated into the top controller unit.

In one embodiment, the controller unit is programmed in accordance withthe user's prescription. This can be done by means of an initial setupin which the user places all the packets of prescription additives oneby one on the scale tray. The measurements made by the digital scale arerecorded and stored in an internal memory. The controller thus hasaccess to the data regarding names and prescribed weights of theadditives. Therefore, when a packet of any prescription additive isplaced on the scale for measurement prior to starting the dialysisprocess, the controller compares the measured weight with the prescribedweight stored in an internal memory. In case of any discrepancy betweenthe measured weight and the correct or prescribed weight, the controllerdirects the GUI to display an alarm or directs an audio generation unitto generate an auditory alarm. Therefore, such an alarm may be visual,such as a flashing error message on the GUI screen, and may also beaccompanied by an audible alarm. Alternatively, a user is not permittedto continue the dialysis set up process.

FIG. 79 illustrates an exemplary table of data for prescriptionadditives that may be stored as a file, flat file, or table in theinternal memory of the portable dialysis system. Column 7901 describesthe packet contents and column 7902 shows the corresponding weight. Ascan be seen from column 7902, the weight difference between thedifferent packages is several grams, which can be read by a digitalscale. In one embodiment, the digital scale of the present invention isdesigned with a weight resolution of the order of 0.1 gm, which, giventhe weight of additives, provides a greater than 5 times resolutionadvantage and, more preferably, 10 times resolution advantage. Thisresolution is sufficient to differentiate between the typically usedadditives.

Optionally, the structure of the digital scale is designed such that theweighing process is not affected by the manner in which a user placesthe packets of prescription additives on the scale. This is because thestructure of the scale in the present invention comprises multipleweight-sensitive members at multiple suspension points. In oneembodiment for example, the scale comprises three sensors on a threepoint suspension. The total weight is computed by the scale system asthe SUM of that measured by all the sensors. The advantage of using thiscomputing scheme is that the packet weight need not be evenlydistributed on the scale platform. Thus, even if the packets are placedon the scale tray slightly off to one side, flat or scrunched, it wouldnot affect the accuracy of weight measurement made by the scale. Thatis, a user is not constrained in the manner in which he places thepackets on the scale.

It should further be appreciated that the sensor weight can bedetermined using any calculation method known in the art. In oneembodiment, a processor in data communication with the scale receivesdata readings from the scale and determines a weight as follows:

Sensor_Weight(i)=K1(i)*ADC(reading)+K0(i)

Bag_Weight=(Sensor_Weight(0)+Sensor_Weight(1)+Sensor_Weight(2)+Sensor_Weight(3))/4

As previously discussed with respect to FIG. 16, the portable dialysissystem has an exposed reader 1605, such as a bar code reader or RFID tagreader, which can be used to read codes or tags on the packets ofprescribed additives. For initial setup, a user would preferably swipeall of the codes/tags on the packets of prescription additives by thereader 1605. The user can be assisted through an initial GUI messagewhich prompts the user to swipe each packet of prescription additivepass the reader 1605. Upon doing so, the reader obtains identifyinginformation about the additive and transmits that identifyinginformation to an internal table stored in memory. After this initialsetup, whenever a prescription additive is to be added to the dialysateprior to starting dialysis, the identifying information of the concernedpacket (read by the reader 1605) is compared to the identifyinginformation for that additive already stored in the internal tableduring initial setup. This helps to verify that the correct additiveshave been selected for use with the dialysate and helps rule out anyspurious additives. The contents of the internal table can be generatedeither by manual input of data regarding the identity and weight of theadditives or by remote access to a prescription that details theidentity and amount of the additives.

In one embodiment, the GUI of the present invention is generated by aplurality of programmatic instructions stored and executed by aprocessor resident in the controller unit. One set of programmaticinstructions is designed to walk a user through a process for verifyingthe identity and amount of additives to be used. A first GUI screenprompts a user to expose a bar code on an additive bag to the bar codereader. One of ordinary skill in the art would appreciate that thisidentifying mechanism can be a bar code, RFID tag, or other electronictag, and the reader can be a bar code reader, RFID tag reader, or otherelectronic tag reader. The reader reads the coded information, processesit using a processor, and transmits the processed information to amemory. The memory has a programmatic routine that translates theprocessed information into an identity of an additive. In oneembodiment, the translation is facilitated by a table that matchesvarious identifiers to specific additive names. This table can bemanually inputted prior to the procedure or downloaded from a server viaa wired or wireless connection to the controller.

Once the additive identity is obtained, the GUI communicates theidentity of the additive to the user and instructs the user to place theadditive on the scale. The digital scale weighs the additive andcommunicates the measured weight to a second table. The second tablemaps the additive identity with the expected weight. This second tablemay be manually inputted prior to the procedure or downloaded from aserver via a wired or wireless connection to the controller. If theadditive identity and measured weight match, the user is instructed toopen the packet and pour the contents into the appropriate location.This process is repeated for all the additives. In one embodiment, auser is not permitted to continue the process if there is a discrepancybetween the identity of the packet and its weight or if the codedidentity of the packet cannot be read or is unknown. Thus, the systemprovides a one step or two-step verification mechanism: a) using thedigital scale by itself or b) using the digital scale in combinationwith the bar code or tag reader, which ensures that the user has, in hisor her possession, all of the required additives and that the correctadditives are being used and not counterfeit or unsuitable.

Referring to FIG. 80, a flowchart showing another process 8000 forinitiating a dialysis treatment is shown. In one embodiment, thecontroller unit 8001 comprises at least one processor and memory storinga plurality of programmatic instructions. When executed by theprocessor, the programmatic instructions generate a plurality ofgraphical user interfaces, displayed on the controller display, whichdirects a user through a series of actions designed to reliably acquireand measure the additives required for use in a dialysis treatment. Afirst graphical user interface is generated through which a user canprompt the system to initiate the additive accounting process 8001. Theinitial prompt can be through a specific icon for initiating the processor can occur as part of a larger system setup.

A second graphical user interface is then generated 8003 which displaysin text or graphical form the additives required, preferably including avisual image of the actual additive package to permit a user to visuallycompare the additive required with the product the user has on-hand. Theuser is then prompted 8005 to indicate whether he wishes to verify theadditive using a bar code scan or by weight. If the user indicates hewishes to use the bar code scan, through, for example, pressing an icon,a third graphical user interface is generated 8007 prompting the user topass the first additive past the bar code scanner. The user then passesan additive, preferably in any order, past the bar code scanner,registering a read. It should be appreciated that the bar code scannercan comprise a light, such as a red light, which changes color, such asto green, upon a successful reading.

If the system successfully reads the bar code it processes 8009 the codeby checking the code against a table stored in memory. The table storedin memory associates bar codes with specific additives. Once a specificadditive is identified, the second graphical user interface, asdescribed above, is updated 8011 with a check mark or highlight toindicate which additive has been successfully scanned and the user isinstructed to set the additive aside. This process is repeated 8019 forall additives. In one embodiment, once all additives are highlighted orchecked, the system automatically proceeds to the next step in thedialysis set up or initialization process. In another embodiment, onceall additives are highlighted or checked, the system presents agraphical user interface informing the user that all additives have beenregistered, after which a user causes the system to manually proceed tothe next step in the dialysis set up or initialization process. Itshould be appreciated that, while the term bar code is used, anyelectronic tagging or labeling system can be used.

If, for any scanning step 8009 the bar code is not recognized, theadditives do not have bar codes, or the user prefers to verify additivesusing weighing, as opposed to scanning, a graphical user interface ispresented to the user prompting 8013 the user to place a first additiveon the scale. The scale measures the additive package weight 8015 andcompares the measured weight to a table of weight values associated withspecific additives in order to recognize the additive. Once recognized,the second graphical user interface, as described above, is updated 8017with a check mark or highlight to indicate which additive has beensuccessfully scanned and the user is instructed to set the additiveaside. This process is repeated 8019 for all additives. In oneembodiment, once all additives are highlighted or checked, the systemautomatically proceeds to the next step in the dialysis set up orinitialization process. In another embodiment, once all additives arehighlighted or checked, the system presents a graphical user interfaceinforming the user that all additives have been registered, after whicha user causes the system to manually proceed to the next step in thedialysis set up or initialization process. It should be appreciatedthat, while the term bar code is used, any electronic tagging orlabeling system can be used.

If the additive is not recognized, the user is informed that theadditive is not part of the treatment process and is prompted to weigh aproper additive. In another embodiment, if the user fails to scan orweigh a recognized additive, the user is not permitted to continue theinitialization or set up process.

One of ordinary skill in the art would appreciate that although theaforementioned verification procedure has been described forprescription additives, the same procedure may also be extended to thedisposable components used with the dialysis system, such as sorbentcartridges and other disposables.

It should further be appreciated that the process of scanning andweighing the additives can be integrated and automated. As discussedabove, a user can be prompted to initiate the additive weighing processand a display of items needed for treatment may be displayed. A userplaces an additive on a scale which has a bar code reader proximate toor integrated therein. In one embodiment, the user is prompted to placethe additive in a specific position or configuration to ensure the barcode can be properly read. Upon placing the additive on the scale havingan integrated or combined bar code reader, the bar code reader scans theadditive, attempts to recognize the bar code, and, if recognized,processes the item by checking or highlighting the identified additiveon the display. If the bar code reader fails to identify the additive,if the system requires an additional, supplemental check, or if thesystem wishes to obtain or otherwise record weight information, thescale measures the weight and attempts to recognize the additive againststored values. If identified, the system processes the item by checkingor highlighting the identified additive on the display. The scalemeasurement and bar code reader can therefore occur without having tomove the additive from one location or position to another.

It should further be appreciated that the additives can be inserted intoa holding container, chute, cylinder, box, bucket, or staging area thatwill automatically drop, place, or otherwise position each additive intothe appropriate position on a scale/bar code reader. Accordingly, theuser can place all additives into a single container, activate thesystem, and have each additive sequentially positioned on the scale andidentified automatically. A user may be prompted to remove each additiveafter each additive is recognized or may be prompted to allow alladditives to be processed first.

It should further be appreciated that the additive can be added to thesystem automatically after identification, manually afteridentification, and either before or after the hemofilter and/or sorbentcartridge is installed. In one embodiment, the top or bottom unit of theportable dialysis system also preferably has electronic interfaces, suchas Ethernet connections or USB ports, to enable a direct connection to anetwork, thereby facilitating remote prescription verification,compliance vigilance, and other remote servicing operations. The USBports also permit direct connection to accessory products such as bloodpressure monitors or hematocrit/saturation monitors. The interfaces areelectronically isolated, thereby ensuring patient safety regardless ofthe quality of the interfacing device.

In another embodiment, the dialysis machine comprises an interface, inthe form of a graphical user interface with touch screen buttons,physical keypad, or mouse, which can be manipulated to cause a dialysismachine loaded with a manifold to start operation in either a treatmentmode or priming mode. When instructed to operate in treatment mode, thecontroller generates a signal (in response to that treatment modecommand) to cause the manifold valve to switch from an open, primingstate to a closed, treatment state. When instructed to operate inpriming mode, the controller generates a signal (in response to thatpriming mode command) to cause the manifold valve to switch from aclosed, treatment state to an open, priming state. One of ordinary skillin the art would appreciate that all of the aforementioned control anduser command functions are effectuated by incorporating one or moreprocessors executing programming embodying the aforementionedinstructions, which are stored in local memory.

When properly actuated, the system can operate in at least a primingmode and a treatment mode, which can comprise other modes of operation(such as hemodialysis, hemofiltration, or, simply, a non-priming mode).With respect to an exemplary treatment mode and referring to FIG. 84,the dialysis system 8400 operating in dialysis mode comprises a dialyzer8402, sorbent regeneration system (e.g. cartridge) 8412, manifold 8410,infusate source 8416 entering into the manifold 8410 through a port, andreservoir 8415 from which fresh dialysate is input back into themanifold 8410 via a port. In operation, blood enters the blood line8401, into the manifold 8410 through a port, through a two-way valve8421 which is in a first position, and into the dialyzer 8402. Thepurified blood exits the dialyzer 8402 through outlet 8403, through atwo-way valve 8422 which is in a first position, and into the manifold8410 through a port. The blood passes through the manifold, passingthrough a plurality of valves 8417, as described above in relation tomanifold 8410, and out of a port and into a blood line 8423 entering thepatient.

Concurrently, infusate passing from a source 8416 passes into themanifold 8410 through a port, through the manifold 8410, out throughanother port, and into reservoir 8415, from which dialysate is deliveredvia a dialysate in-line 8424 and into dialyzer 8402. After passingthrough the dialyzer 8402, the dialysate passes through an out-line 8425and back into the manifold 8410 through a port where it is routed to thesorbent-based dialysate regeneration system 8412 via a port. Regenerateddialysate passes back through the manifold 8410 via a port and isre-circulated through the dialyzer 8402 with new dialysate, if and whenrequired. To manage dialysate fluid flow, a reservoir 8415 is used tostore regenerated dialysate, if and when needed. In one embodiment, thereservoir holds 5 liters of dialysate and has the capacity to hold up to10 liters of dialysate and effluent from the patient.

With respect to an exemplary priming mode and referring to FIG. 85, adialysis system 8500 operating in priming mode comprises a dialyzer8502, sorbent regeneration system (e.g. cartridge) 8512, manifold 8510,infusate source 8516, and reservoir 8515. In operation, the bloodlinefrom the patient (e.g. 8401 in FIG. 84) into the manifold 8510 is notconnected and therefore, no blood is flowing, or capable of flowing,into the manifold 8510. Rather, dialysate passing from a source 8515passes into the manifold 8510 through a plurality of ports and through adialysate in-line 8524, which is connected to the two-way valve port8522.

In a preferred embodiment, a single two-way valve 8517 is incorporatedinto the physical body of the manifold 8510 and manipulated to switchbetween a treatment mode of operation and a priming mode of operation,as discussed above. In this embodiment, a manifold 8510 comprises atwo-way valve 8517 which, if activated or switched from a firstpositioned (e.g. closed) to a second position (e.g. open), causes achange to the internal flow path of liquid within the manifold. As aresult of this flow path change, the blood and dialysate circuits,which, when the valve is closed, are fluidically isolated from eachother, are now placed in fluid communication with each other.Preferably, no additional valves or switches need to be manipulated inorder to achieve this state change, namely, to cause separate blood anddialysate circuits to become fluidly connected.

The valve switch may be effectuated by any means known in the art,including by physically manipulating a mechanical control on the surfaceof the manifold or electronically through the operation of a dialysismachine causing a change to the valve state through an interface betweenthe dialysis machine, which has a controller to control the state of thevalve in accordance with a user selected operational mode, and a valveinterface integrated into the surface of the manifold.

In priming mode, the valve 8517 would be opened, thereby causingdialysate fluid flowing through a pump to pass through the manifold8510, into the dialyzer 8502 via tubes 8524, 8503 and two-way valve port8522, out of the dialyzer, back into the manifold 8510 via two-way valveport 8521 and tube 8525, and out of manifold 8510. Accordingly, in thepriming mode, the valve 8517 ensures that the dialysate circulatesthrough the blood circuit, thereby placing the blood and dialysatecircuits in fluid communication. Functionally, the manifold 8510 isplaced in priming mode by manipulating the state of the two-way valve8517.

After a specified volume of dialysate is pumped into and through theblood circuit, the two-way valve is closed. Pumping of dialysate may ormay not continue. If continued, the fresh dialysate circulates throughthe dialysate circuit only. In the blood circuit, residual dialysateremains. To purge the dialysate from the blood circuit, a patient isconnected to the “From Patient Line” 8401, shown in FIG. 84 andtypically referred to as the arterial access line. The “To Patient Line”8423, typically referred to as the venous return line is either heldover a waste container or connected to a patient.

By placing the system in treatment mode, blood from the patient is drawninto the blood circuit, passing into the manifold, through pumps, out ofthe manifold, through the dialyzer, back into the manifold, and back outof the manifold. The blood thereby causes the residual priming fluid tobe ‘chased’ through the blood circuit, removing any remaining airpockets in the process, and into either a waste container or thepatient, depending on the connected state of the venous return line.After blood has completely filled the blood circuit, the system stopsthe blood pump or the user stops the pump manually. If not alreadyconnected, the venous return line is then connected to the patient andthe treatment continues.

In another embodiment, a filter, such as a 0.22μ filter, can be used tohelp remove any remaining undesirable substances if the sorbent-canisteris inadequate to produce essentially sterile dialysate. In oneembodiment, the filter is positioned in-line with the reservoir inputline, proximate to Port E of the manifold, and is used both duringpriming and operation.

By using this priming system, one avoids having to use an additional andseparate set of disposables to just prime the blood side of the circuit.In particular, this approach eliminates the need for a separate salinesource, such as a 1 liter bag of saline, and, accordingly, alsoeliminates the need for connectors and tubing to the separate salinesource, including dual-lumen spikes or single lumen spikes used toconnect blood lines to the saline.

Disposable Kits

Embodiments of the dialysis system disclosed herein are designed to usea plurality of disposable components. Referring to FIG. 81, in oneembodiment, disposables 8106 for use in the system are shipped inpackaging preassembled on a tray 8105. The tray 8105 is placed on top ofthe controller unit 8101 workspace, thereby permitting easy access to,and management of, the required disposables, which is of particularimportance for home users. The controller unit 8101 is waterproof ratedso that in case of a liquid spill, it should not seep into and damagethe top controller unit 8101.

In one embodiment, the kit 8200 contains a manifold 8202, dialyzer 8201,and tubing 8203 which are all preattached. Referring to FIG. 82, thedisposable kit 8200 comprises a dialyzer 8201, manifold 8202, tubing8203, valves 8204 (as part of the manifold), reservoir bag 8205, whichare all preattached and configured for direct installation into thedialysis machine by a user.

More specifically, the disposable components, particularly the fullydisposable blood and dialysate circuits, are prepackaged in a kit (whichincludes dialyzer, manifold, tubing, reservoir bag, ammonia sensor, andother components) and then installed by a user by opening the front doorof the top unit (as discussed above), installing the dialyzer andinstalling the manifold in a manner that ensures alignment againstnon-disposable components such as pressure sensors and other components.A plurality of pump shoes integrated into the internal surface of thefront door makes loading of disposable components easy. The manifoldonly needs to be inserted and no pump tubing needs to be threadedbetween the rollers and shoes. This packaged, simple approach enableseasy disposables loading and cleaning of the system. It also ensuresthat the flow circuitry is properly configured and ready for use. Inoperation, the top unit is attached to the bottom unit with reservoir.

Optionally, the disposable components, and particularly the manifold,comprise an electronic-based lockout (“e-lockout”) system. FIG. 83 is afunctional block diagram showing one embodiment of the e-lockout systemof the present invention. In one embodiment, e-lockout system 8300comprises a reader 8301 that detects and reads identification data 8306embedded in disposable items 8302, such as disposable manifolds,disposable sorbents used in dialysate regeneration and/or dialyzers. Theidentification data 8306 may be stored on disposable items 8302 viabarcode, RFID tags, EEPROM, microchip or any other identification meansthat uniquely identifies the disposable items 8302 to be used in thedialysis system 8303. The reader 8301 is correspondingly a barcodereader, RFID reader, microchip reader, or any other reader thatcorresponds to the identification technology employed as is known topersons of ordinary skill in the art. In one embodiment, the reader 8301is connected with a transceiver for wirelessly connecting to a remotedatabase 8305 through a network 8304 such as the Internet or any otherpublic or private network known to persons of ordinary skill in the art.In another embodiment, the reader 8301 is directly aligned with theidentification data 8306.

The database 8305, located remote from the dialysis system, stores aplurality of information about the disposable items 8302 that can beused in the system 8303. The information comprises unique identificationdata 8306 along with information for the corresponding disposable itemsuch as authenticity, usability in terms of whether or not the item islikely to be in working condition, or if the item has been recalled bythe manufacturer owing to a defect, its expiry date, if any, and/or anyother such value-added information that would advantageously be evidentto persons of ordinary skill in the art.

In operation, when a disposable item 8302, such as a dialyzer, manifold,or a hemofilter cartridge, is loaded into the system 8303 the reader8301 detects the disposable item 8302 through identification data 8306embedded onto item 8302. This identification data 8306 is read by reader8301, which, in turn, communicates, either wired or wirelessly, withdatabase 8305 to request more information on the item 8302 storedtherein, based on identification data 8306, or confirm the validity orintegrity of the item 8302 based on identification data 8306.

For example, in one embodiment, dialyzer cartridge 8302 identified bythe reader 8301 may have been called back by the manufacturer on accountof some defect. This call-back information is stored on the database8305 and is returned back to the reader 8301 as a result of the requestsignal sent by the reader 8301 to the database 8305 through the network8304. As a result of the call-back information received from thedatabase 8305, the microprocessor controlling the blood purificationsystem supported by the system 8303 does not allow the user to proceedwith treatment. This is achieved, in one embodiment, by suspendingfunctioning of the pumps that propel fluids through the fluid circuitsof the blood purification system 8303. Additionally, an audio/visualalarm may also be displayed to this effect.

In another example, dialyzer cartridge 8302 identified by the reader8301 may not be authentic. As a result of which, the microprocessorwould not allow functioning of the blood purification system of thesystem 8303. Thus, the e-lockout system 8300 of the present inventionprevents usage of the system 8303 in case the disposable items 8302attached to the manifold 8303 are in a compromised state.

While there has been illustrated and described what is at presentconsidered to be a preferred embodiment of the present invention, itwill be understood by those skilled in the art that various changes andmodifications may be made, and equivalents may be substituted forelements thereof without departing from the true scope of the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the central scope thereof. Therefore, it is intended thatthis invention not be limited to the particular embodiment disclosed asthe best mode contemplated for carrying out the invention, but that theinvention will include all embodiments falling within the scope of theappended claims.

We claim:
 1. A dialysis machine having a reservoir unit wherein saidreservoir unit comprises: a. a first housing having an external surfaceand an internal surface and defining a first volume adapted to hold afluid therein; b. a second housing having an external surface and aninternal surface and defining a second volume adapted to house the firsthousing with a space between the external surface of the first housingand the internal surface of the second housing; c. a heating elementpositioned within the space between the external surface of the firsthousing and the internal surface of the second housing; and d. a firstplurality of electrical contacts attached to the external surface of thesecond housing and electrically coupled to the heating element.
 2. Thedialysis machine of claim 1, wherein said first housing is fused to saidsecond housing.
 3. The dialysis machine of claim 1, wherein said heatingelement is a heating pad and wherein said heating pad is rated in arange from 300 W to 600 W.
 4. The dialysis machine of claim 3, whereinsaid heating pad is configured to heat from 1 to 6 liters of a fluid,located within said first volume, to a temperature within a range of 36to 39 degrees C. within 15 to 45 minutes.
 5. The dialysis machine ofclaim 1, wherein said first housing is a pan and wherein the firstvolume is at least one of a cuboid, right rectangular prism, rectangularprism, or rectangular parallelepiped.
 6. The dialysis machine of claim5, wherein said second housing is a pan and wherein the second volume isat least one of a cuboid, right rectangular prism, rectangular prism, orrectangular parallelepiped.
 7. The dialysis machine of claim 1, whereinthe first plurality of electrical contacts attached to the externalsurface of the second housing are electrically coupled to the heatingelement by wires that extend from the heating element through the secondhousing and into the electrical contacts.
 8. The dialysis machine ofclaim 1 further comprising: a. a base unit, having a length extendingfrom a front of the base unit to the back of the base unit, wherein thebase unit comprises a support point; b. a first internal frame connectedto said support point, wherein said first internal frame comprises: i. aplate comprising a second plurality of electrical contact elementsconnected to a power supply of the dialysis machine; ii. at least twofirst tracks, with each first track physically coupled to said plate andextending across the length of the base unit.
 9. The dialysis machine ofclaim 8 wherein said second housing comprises a plurality of top edgesand wherein linear extensions perpendicularly extend from at least twoof said top edges.
 10. The dialysis machine of claim 9 wherein saidreservoir unit is installed in said dialysis machine by sliding saidlinear extensions onto said first tracks until a predefined insertionpoint.
 11. The dialysis machine of claim 10 wherein, upon the reservoirunit sliding on said first tracks and reaching said predefined insertionportion, the first plurality of electrical contact elements electricallycouples with said second plurality of electrical contact elements. 12.The dialysis machine of claim 8 wherein said first internal frame isonly physically coupled to the base unit through the support point. 13.The dialysis machine of claim 8 wherein the support point comprises aflexure assembly, wherein said flexure assembly is adapted to measure aweight of contents located within said first volume.
 14. The dialysismachine of claim 10, wherein each of said at least two first trackscomprises a positioning tab demarcating a drop off section and whereinsaid reservoir unit drops off of said tracks and into place when fullyinserted into said reservoir unit support structure.
 15. The dialysismachine of claim 8, wherein said base unit further comprises a topmember attached to a second internal frame, said second internal framecomprising at least two second tracks, with each second track extendingacross the length of the base unit.
 16. The dialysis machine of claim15, wherein said second tracks are configured to suspend a ceilingelement, said ceiling element comprising: a. a lining bag configured torest in a reservoir unit and hold a liquid; b. at least one first tubefor drawing said liquid from said reservoir unit; and c. at least onesecond tube for returning said liquid to said reservoir unit.
 17. Thedialysis machine of claim 16, further comprising a door on a front ofsaid base unit, wherein said door folds upward to close and foldsdownward to open.
 18. A pump shoe for a pumping system having flexibletubing wherein said tubing is compressed against said pump shoe by apump roller during operation, said pump shoe comprising: a. a contactsurface for receiving said tubing, wherein said contact surface has adegree of curvature matching the curvature of said pump roller andimparting a concave shape for receiving said tubing as it is compressedby said pump roller; b. an attachment surface opposite said contactsurface for attachment of said pump shoe to said pumping system; and, c.two side surfaces, opposite one another and perpendicular to saidcontact and attachment surfaces, wherein the edge of each side surfaceadjacent said contact surface extends outwardly beyond said contactsurface, forming elevated side walls to contain said tubing and adaptedto prevent lateral movement of said tubing along said contact surfaceduring operation.
 19. The pump shoe of claim 18, wherein said sidesurfaces extend outwardly beyond said contact surface by 0.060 to 0.095inches.
 20. The pump shoe of claim 18, wherein said side surfacesadditionally extend inwardly along said contact surface by 0.001 to0.185 inches.
 21. The pump shoe of claim 18, wherein said side surfaceshave the same degree of concave curvature as said contact surface.